Lithocholic acid feeding results in direct hepato-toxicity independent of neutrophil function in mice

Abstract

Lithocholic acid (LCA) supplementation in the diet results in intrahepatic cholestasis and bile infarcts. Previously we showed that an innate immune response is critical for cholestatic liver injury in the bile duct ligated mice. Thus, the purpose of this study was to investigate the role of neutrophils in the mechanism of liver injury caused by feeding mice a diet containing LCA. C57BL/6 mice were given control or 1% LCA containing diet for 24–96h and then examined for parameters of hepatotoxicity. Plasma ALT levels were significantly increased by 48h after LCA feeding, which correlated with both neutrophil recruitment to the liver and upregulation of numerous pro-inflammatory genes. The injury was confirmed by histology. Deficiency in intercellular adhesion molecule-1 (ICAM-1) expression or inhibition of neutrophil function failed to protect against the injury. Bile acid levels were quantified in plasma and bile of LCA-fed mice after 48 and 96h. Only the observed biliary levels of taurochenodeoxycholic acid and potentially tauro-LCA caused direct cytotoxicity in mouse hepatocytes. These data support the conclusion that neutrophil recruitment occurs after the onset of bile acid-induced necrosis in LCA-fed animals, and is not a primary mechanism of cell death when cholestasis occurs through accumulation of hydrophobic bile acids.

Dual action of peroxisome proliferator-activated receptor alpha in perfluorodecanoic acid-induced hepatotoxicity

“…In cholestasis induced by LCA, the liver injury is caused by an overload of bile acids (Woolbright et al 2014;Yu et al 2015). Super increase in ALT and severe necrosis in the liver tissues were reported when the ALP increased by twofold (Woolbright et al 2014).…”

Sweroside ameliorates α-naphthylisothiocyanate-induced cholestatic liver injury in mice by regulating bile acids and suppressing pro-inflammatory responses

“…Bile acids play an important role in the enterohepatic system, but the corresponding cytotoxicity to hepatocytes should also be addressed [1,2] . Numerous studies have suggested that the intrahepatic accumulation of bile acids may directly or indirectly cause further damage to the liver [3] .…”

Critical Factors in the Assessment of Cholestatic Liver Injury In Vitro

“…Perhaps the most important aspect of these new data is the elucidation of vast differences in individual bile acid concentrations in rodents and humans, both in control patients and during cholestatic liver injury [1]. While numerous studies [6, 12, 13] have focused on administering micromolar levels of toxic bile acids or their conjugate salt, such as glycochenodeoxycholate (GCDC) or taurolithocholate (TLC), to hepatocytes in vitro, newer data based on mass spectrometric bile acid analysis questions the use of micromolar concentrations of these bile acids in rodent cultures, as they likely do not accumulate to similar values in any compartment in vivo [8, 10]. Moreover, murine hepatocytes are highly resistant to TLC-induced injury in vitro, suggesting mechanisms of toxicity specific to the rat [10, 14].…”

“…While numerous studies [6, 12, 13] have focused on administering micromolar levels of toxic bile acids or their conjugate salt, such as glycochenodeoxycholate (GCDC) or taurolithocholate (TLC), to hepatocytes in vitro, newer data based on mass spectrometric bile acid analysis questions the use of micromolar concentrations of these bile acids in rodent cultures, as they likely do not accumulate to similar values in any compartment in vivo [8, 10]. Moreover, murine hepatocytes are highly resistant to TLC-induced injury in vitro, suggesting mechanisms of toxicity specific to the rat [10, 14]. Additionally, the use of unconjugated bile acids to investigate pathophysiology seems unwarranted as more than 99 % of bile acids in liver, plasma and bile are conjugated to taurine or glycine in multiple species [7–9, 11].…”

“…Additionally, the use of unconjugated bile acids to investigate pathophysiology seems unwarranted as more than 99 % of bile acids in liver, plasma and bile are conjugated to taurine or glycine in multiple species [7–9, 11]. While intrahepatic concentrations of bile acids are considered to be integral to the injury, recent reports have asserted that the characteristic areas of necrosis seen after BDL or after administration of 1 % LCA via the diet are due to infarction of the small biliary tracts and the ensuing release of bile into the hepatic parenchyma, suggesting that biliary levels of bile acids may be driving the hepatic accumulation of bile acids during some models of cholestatic liver injury [2, 10]. Cholestasis models, such as BDL, display a lack of zonation in the area of injury.…”