Induction of innate immune response and absence of subsequent tolerance to dsRNA in biliary epithelial cells relate to the pathogenesis of biliary atresia

Background/Aims: Biliary epithelial cells (BECs) possess negative regulatory mechanisms of Toll‐like receptor (TLR)‐based tolerance to bacteria (e.g. endotoxin tolerance). Viral infections of the Reoviridae genus with a dsRNA genome are suspected to be part of the aetiology of biliary atresia (BA), but the negative biliary mechanisms remain unexplored. Methods: Cultured human intrahepatic BECs (HIBECs) pretreated with polyinosinic–polycytidylic acid [poly(I:C)] (a synthetic analogue of viral dsRNA) for 24 h were exposed to poly(I:C) in fresh medium. The activation of nuclear factor‐κB (NF‐κB) and the expression of myxovirus resistance protein A (MxA) and tumour necrosis factor‐related apoptosis‐inducing ligand (TRAIL) mRNAs were evaluated. Moreover, after the pretreatment, the transition of these molecules was examined in poly(I:C)‐free conditions. Results: Treatment with poly(I:C) significantly upregulated NF‐κB activity in fresh HIBECs, and pretreatment failed to show tolerance to poly(I:C). The production of MxA and TRAIL was also preserved. Moreover, upregulation in the pretreated HIBECs was well preserved in poly(I:C)‐free medium for at least 72 h. Conclusions: BECs fail to show tolerance to poly(I:C), and once innate immunity is activated it is sustained in poly(I:C)‐free conditions, suggesting that the initiation of the immune response to dsRNA in HIBECs and its presence after the clearance of virus are closely associated with the progression of BA.