title: Protective effect of heme oxygenase induction in ethinylestradiol-induced cholestasis.
abstract: Estrogen-induced cholestasis is characterized by impaired hepatic uptake and biliary bile acids secretion because of changes in hepatocyte transporter expression. The induction of heme oxygenase-1 (HMOX1), the inducible isozyme in heme catabolism, is mediated via the Bach1/Nrf2 pathway, and protects livers from toxic, oxidative and inflammatory insults. However, its role in cholestasis remains unknown. Here, we investigated the effects of HMOX1 induction by heme on ethinylestradiol-induced cholestasis and possible underlying mechanisms. Wistar rats were given ethinylestradiol (5 mg/kg s.c.) for 5 days. HMOX1 was induced by heme (15 μmol/kg i.p.) 24 hrs prior to ethinylestradiol. Serum cholestatic markers, hepatocyte and renal membrane transporter expression, and biliary and urinary bile acids excretion were quantified. Ethinylestradiol significantly increased cholestatic markers (P ≤ 0.01), decreased biliary bile acid excretion (39%, P = 0.01), down-regulated hepatocyte transporters (Ntcp/Oatp1b2/Oatp1a4/Mrp2, P ≤ 0.05), and up-regulated Mrp3 (348%, P ≤ 0.05). Heme pre-treatment normalized cholestatic markers, increased biliary bile acid excretion (167%, P ≤ 0.05) and up-regulated hepatocyte transporter expression. Moreover, heme induced Mrp3 expression in control (319%, P ≤ 0.05) and ethinylestradiol-treated rats (512%, P ≤ 0.05). In primary rat hepatocytes, Nrf2 silencing completely abolished heme-induced Mrp3 expression. Additionally, heme significantly increased urinary bile acid clearance via up-regulation (Mrp2/Mrp4) or down-regulation (Mrp3) of renal transporters (P ≤ 0.05). We conclude that HMOX1 induction by heme increases hepatocyte transporter expression, subsequently stimulating bile flow in cholestasis. Also, heme stimulates hepatic Mrp3 expression via a Nrf2-dependent mechanism. Bile acids transported by Mrp3 to the plasma are highly cleared into the urine, resulting in normal plasma bile acid levels. Thus, HMOX1 induction may be a potential therapeutic strategy for the treatment of ethinylestradiol-induced cholestasis.
authors: Institute of Medical Biochemistry and Laboratory Diagnostics, 1st Faculty of Medicine, Charles University in Prague, Prague, Czech Republic.
authors: Lucie
authors: L
authors: Muchova
authors: Katerina
authors: K
authors: Vanova
authors: Jakub
authors: J
authors: Suk
authors: Stanislav
authors: S
authors: Micuda
authors: Eva
authors: E
authors: Dolezelova
authors: Leos
authors: L
authors: Fuksa
authors: Dalibor
authors: D
authors: Cerny
authors: Hassan
authors: H
authors: Farghali
authors: Miroslava
authors: M
authors: Zelenkova
authors: Martin
authors: M
authors: Lenicek
authors: Ronald J
authors: RJ
authors: Wong
authors: Hendrik J
authors: HJ
authors: Vreman
authors: Libor
authors: L
authors: Vitek
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000235:genetics; D000469:Alkaline Phosphatase / Q000097:blood; D000818:Animals; D001647:Bile Acids and Salts / Q000097:blood; D001663:Bilirubin / Q000097:blood / Q000494:pharmacology; D002478:Cells, Cultured; D002779:Cholestasis / Q000097:blood / Q000139:chemically induced / Q000201:enzymology*; D004790:Enzyme Induction / Q000187:drug effects; D004997:Ethinyl Estradiol; D005260:Female; D015870:Gene Expression / Q000187:drug effects; D006418:Heme / Q000494:pharmacology*; D006419:Heme Oxygenase (Decyclizing) / Q000096:biosynthesis* / Q000235:genetics; D022781:Hepatocytes / Q000187:drug effects / Q000201:enzymology; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000235:genetics; D061251:Primary Cell Culture; D020011:Protective Agents / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013656:Taurocholic Acid / Q000494:pharmacology
chemical_list: D018528:ATP-Binding Cassette Transporters; D000469:Alkaline Phosphatase; D001647:Bile Acids and Salts; D001663:Bilirubin; D004997:Ethinyl Estradiol; D006418:Heme; D006419:Heme Oxygenase (Decyclizing); D027425:ATP-Binding Cassette, Sub-Family C Proteins; D020011:Protective Agents; D013656:Taurocholic Acid; C423013:Abcc2 protein, rat; C489542:Abcc4 protein, rat
keywords: 17α- ethinylestradiol; bile acids; heme; multidrug resistance-associated protein 3; nuclear factor erythroid-2-related factor-2