Dexamethasone counteracts hepatic inflammation and oxidative stress in cholestatic rats via CAR activation

PLoS One. 2018 Sep 25;13(9):e0204336. doi: 10.1371/journal.pone.0204336. eCollection 2018.

Abstract

Glucocorticoids (GCs) are currently used for the therapeutic management of cholestatic diseases, but their use and molecular mechanism remain controversial. The aims of this study were 1) to assess the therapeutic effect of a 2-week treatment with the GC dexamethasone on hepatic damage in bile duct-ligated rats; 2) to investigate its effect on the activation of the nuclear receptors (NRs) pregnane X receptor (PXR), constitutive androstane receptor (CAR) and GC receptor (GR), and NF-kB, as well as on oxidative stress and bile acid (BA) hepatic composition. Cholestasis was induced by ligation of bile duct (BDL animals) in 16 male Wistar-Kyoto rats, and eight of them were daily treated by oral gavage with 0.125 mg/ml/kg DEX for 14 days. Eight Sham-operated rats were used as controls. Severity of cholestasis was assessed histologically and on plasma biochemical parameters. The nuclear expression of NF-kB (p65), GR, PXR and CAR was measured in hepatic tissue by Western Blot. Oxidative stress was evaluated by measuring malondialdehyde, carbonylated proteins, GHS and ROS content in rat livers. LC-MS was used to measure the plasma and liver concentration of 7 BAs. Histological findings and a significant drop in several markers of inflammation (p65 nuclear translocation, mRNA expressions of TNF-α, IL-1β, IL-6) showed that DEX treatment reversed cholestasis-induced inflammation, and similar results have been obtained with oxidative stress markers. The nuclear expression of p65 and CAR were inversely correlated, with the latter increasing significantly after DEX treatment (p<0.01 vs vehicle). Hepatic BA levels tended to drop in the untreated cholestatic rats, whereas they were similar to those of healthy rats in DEX-treated animals. Plasma BAs decreased significantly in DEX-treated animals with respect to untreated cholestatic rats. In conclusion, DEX reduces inflammation and oxidative stress in BDL rats, and probably CAR is responsible for this effect. Therefore, this NR represents a promising pharmacological target for managing cholestatic and inflammatory liver diseases.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bile Acids and Salts / blood
  • Bile Acids and Salts / metabolism
  • Cholestasis / genetics
  • Cholestasis / metabolism*
  • Cholestasis / pathology
  • Constitutive Androstane Receptor
  • Cytochrome P-450 CYP3A / genetics
  • Cytochrome P-450 CYP3A / metabolism
  • Dexamethasone / pharmacology*
  • Dexamethasone / therapeutic use
  • Gene Expression Regulation, Enzymologic / drug effects
  • Inflammation / drug therapy
  • Liver / drug effects*
  • Liver / metabolism*
  • Liver / pathology
  • Male
  • Oxidative Stress / drug effects*
  • Rats
  • Receptors, Cytoplasmic and Nuclear / metabolism*

Substances

  • Bile Acids and Salts
  • Constitutive Androstane Receptor
  • Receptors, Cytoplasmic and Nuclear
  • Dexamethasone
  • Cytochrome P-450 CYP3A

Grants and funding

This work was supported by grants from the University of Padova (CPDA138721/13 to SDM), and Gilead Inc. (Gilead Fellowship 2015 to SDM). The funders did not have any role in the study design, data collection and analysis, and in the decision to publish, or preparation of the manuscript.