Enhanced innate immune responsiveness and intolerance to intestinal endotoxins in human biliary epithelial cells contributes to chronic cholangitis

Tobias Mueller, Claudia Beutler, Almudena Hurtado Picó, Oren Shibolet, Daniel S. Pratt, Andreas Pascher, Peter Neuhaus, Bertram Wiedenmann, Thomas Berg, Daniel K. Podolsky

Research output: Contribution to journalArticlepeer-review

55 Scopus citations

Abstract

Pattern recognition receptors (PRRs) orchestrate the innate immune defence in human biliary epithelial cells (BECs). Tight control of PRR signalling provides tolerance to physiological amounts of intestinal endotoxins in human bile to avoid constant innate immune activation in BECs. Aims: We wanted to determine whether inappropriate innate immune responses to intestinal endotoxins contribute to the development and perpetuation of chronic biliary inflammation. Methods: We examined PRR-mediated innate immune responses and protective endotoxin tolerance in primary BECs isolated from patients with primary sclerosing cholangitis (PSC), alcoholic liver disease and patients without chronic liver disease. Expression studies comprised northern blots, RT-PCR, Western blots and immunocytochemistry. Functional studies comprised immuno-precipitation Western blots, FACS for endotoxin uptake, and NF-κB activation assays and ELISA for secreted IL-8 and tumour necrosis factor (TNF)-α. Results: Primary BECs from explanted PSC livers showed reversibly increased TLR and NOD protein expression and activation of the MyD88/IRAK signalling complex. Consecutively, PSC BECs exhibited inappropriate innate immune responses to endotoxins and did not develop immune tolerance after repeated endotoxin exposures. This endotoxin hyper-responsiveness was probably because of the stimulatory effect of abundantly expressed IFN-γ and TNF-α in PSC livers, which stimulated TLR4-mediated endotoxin signalling in BECs, leading to increased TLR4-mediated endotoxin incorporation and impaired inactivation of the TLR4 signalling cascade. As TNF-α inhibition partly restored protective innate immune tolerance, endogenous TNF-α secretion probably contributed to inappropriate endotoxin responses in BECs. Conclusion: Inappropriate innate immune responses to intestinal endotoxins and subsequent endotoxin intolerance because of enhanced PRR signalling in BECs probably contribute to chronic cholangitis.

Original languageEnglish (US)
Pages (from-to)1574-1588
Number of pages15
JournalLiver International
Volume31
Issue number10
DOIs
StatePublished - Nov 2011

Keywords

  • Cholangiocyte
  • Innate immune hypo-responsiveness
  • Intestinal endotoxin
  • Nucleotide-binding oligomerization domain protein
  • Primary sclerosing cholangitis
  • Toll-like receptor

ASJC Scopus subject areas

  • Hepatology

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