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

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-?, IL-1?, 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.

SUBMITTER: Gabbia D

PROVIDER: S-EPMC6155538 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature

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

Gabbia Daniela D Pozzo Luisa L Zigiotto Giorgia G Roverso Marco M Sacchi Diana D Dalla Pozza Arianna A Carrara Maria M Bogialli Sara S Floreani Annarosa A Guido Maria M De Martin Sara S

PloS one 20180925 9

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 a ...[more]

PMID: 30252871

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Project description:Mast cells (MCs) are immune cells that release histamine and other mediators. MC number increases after bile duct ligation (BDL) and blocking mast cell-derived histamine decreases biliary proliferation. We aimed to isolate and characterize MCs from cholestatic livers. Rats were subjected to BDL starting at 6 h and up to 14 days. MC infiltration was evaluated by toluidine blue. BDL rats were perfused using standard collagenase perfusion. Following enzymatic digestion, tissue was passed through a fine gauge needle. Suspensions were incubated with MAb AA4, washed and incubated with goat anti-mouse-coated Dynal beads. MCs were stained with toluidine blue, and in isolated MCs the expression of FCɛRI and MC proteases was measured. The expression of histidine decarboxylase, histamine receptors, VEGF receptors, and TIE 1 and 2 was evaluated by qPCR. Histamine and VEGF-A secretion was measured in MC supernatants. MC purity was evaluated by CK-19, CK-8, albumin, VAP-1, and α-SMA expression. In vitro, cholangiocytes and HSCs were treated with isolated MC supernatants from BDL rats treated with either NaCl or cromolyn sodium (to block MC histamine release) and biliary proliferation and hepatic fibrosis were measured. MCs infiltrate the liver and surround bile ducts starting at day 2. We isolated a virtually pure preparation of mature, functional MCs. TEM images reveal distinct secretory granules and isolated MCs secrete histamine. MCs express FCɛRI, chymase, tryptase, RMCP-I, and RMCP-II, but were virtually void of other cell markers. Biliary proliferation and fibrosis increased following treatment with MC supernatants from BDL rats+NaCl and these parameters decreased in cells treated with MC supernatants from BDL+cromolyn sodium. In conclusion, we have isolated and characterized MCs from cholestatic livers. MCs regulate cholestatic liver injury and hepatic fibrosis. This tool provides a better understanding of the paracrine influence of mast cells on biliary/liver pathologies.

Dataset Information

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

Publications

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

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