Bile acid-induced necrosis in primary human hepatocytes and in patients with obstructive cholestasis

Toxicol Appl Pharmacol. 2015 Mar 15;283(3):168-77. doi: 10.1016/j.taap.2015.01.015. Epub 2015 Jan 28.

Abstract

Accumulation of bile acids is a major mediator of cholestatic liver injury. Recent studies indicate bile acid composition between humans and rodents is dramatically different, as humans have a higher percent of glycine conjugated bile acids and increased chenodeoxycholate content, which increases the hydrophobicity index of bile acids. This increase may lead to direct toxicity that kills hepatocytes, and promotes inflammation. To address this issue, this study assessed how pathophysiological concentrations of bile acids measured in cholestatic patients affected primary human hepatocytes. Individual bile acid levels were determined in serum and bile by UPLC/QTOFMS in patients with extrahepatic cholestasis with, or without, concurrent increases in serum transaminases. Bile acid levels increased in serum of patients with liver injury, while biliary levels decreased, implicating infarction of the biliary tracts. To assess bile acid-induced toxicity in man, primary human hepatocytes were treated with relevant concentrations, derived from patient data, of the model bile acid glycochenodeoxycholic acid (GCDC). Treatment with GCDC resulted in necrosis with no increase in apoptotic parameters. This was recapitulated by treatment with biliary bile acid concentrations, but not serum concentrations. Marked elevations in serum full-length cytokeratin-18, high mobility group box 1 protein (HMGB1), and acetylated HMGB1 confirmed inflammatory necrosis in injured patients; only modest elevations in caspase-cleaved cytokeratin-18 were observed. These data suggest human hepatocytes are more resistant to human-relevant bile acids than rodent hepatocytes, and die through necrosis when exposed to bile acids. These mechanisms of cholestasis in humans are fundamentally different to mechanisms observed in rodent models.

Keywords: Bile acids; Biomarkers; HMGB1; Inflammation; Obstructive cholestasis; Primary human hepatocytes.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetylation
  • Animals
  • Bile Acids and Salts / blood
  • Bile Acids and Salts / toxicity*
  • Biomarkers / blood
  • Cells, Cultured
  • Cholestasis, Extrahepatic / blood
  • Cholestasis, Extrahepatic / pathology*
  • Dose-Response Relationship, Drug
  • Glycochenodeoxycholic Acid / toxicity*
  • HMGB1 Protein / blood
  • Hepatocytes / drug effects*
  • Hepatocytes / metabolism
  • Hepatocytes / pathology
  • Humans
  • Jaundice, Obstructive / blood
  • Jaundice, Obstructive / pathology*
  • Keratin-18 / blood
  • Mice, Inbred C57BL
  • Necrosis
  • Primary Cell Culture
  • Species Specificity

Substances

  • Bile Acids and Salts
  • Biomarkers
  • HMGB1 Protein
  • HMGB1 protein, human
  • KRT18 protein, human
  • Keratin-18
  • Glycochenodeoxycholic Acid