RAGE is a key regulator of ductular reaction-mediated fibrosis during cholestasis

Ductular reaction (DR) is the hallmark of cholestatic diseases manifested in the proliferation of bile ductules lined by biliary epithelial cells (BECs). It is commonly associated with increased risk of fibrosis and liver failure. The Receptor for Advanced Glycation End Products (RAGE) was identified as a critical mediator of DR during chronic injury. Yet, the direct link between RAGE-mediated DR and fibrosis as well as the mode of interaction between BECs and hepatic stellate cells (HSCs) to drive fibrosis remains elusive. In this study, we aimed to delineate the specific function of RAGE on BECs during DR and its potential association with fibrosis in the context of cholestasis. Employing a biliary lineage tracing cholestatic liver injury mouse model, combined with whole transcriptome sequencing and in vitro analyses, we revealed the central role of BEC-specific Rage activity in fostering a pro-fibrotic milieu. RAGE is predominantly expressed in BECs and contributes to DR. Notch ligand Jagged1 is secreted from activated BECs in a Rage-dependent manner and signals HSCs in trans, eventually enhancing fibrosis during cholestasis. A mouse line harboring a biliary lineage tracing reporter gene and generated R26TomHnf1b-CreRagefl/fl mice with BEC-specific deletion of Rage (RageΔBEC) was employed. Cholestasis was induced in vivo by the ad libitum Choline-deficient Ethionine-supplemented (CDE) diet. Whole transcriptome sequencing was performed on FACS-sorted primary BECs from CDE-challenged mice to identify Rage-dependent signaling pathways during cholestasis. Using this genetic mouse model, combined with immunohistological analyses, co-culture assays and mass spectrometry analysis, the interplay between BECs and hepatic stellate cells (HSCs) during chronic liver damage was evaluated.