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Keywords:

  • biliary atresia;
  • biliary epithelial cells;
  • innate immunity;
  • liver;
  • tolerance;
  • virus

Abstract

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.