Abstract
Cholestasis causes hepatocyte death, possibly because of mitochondrial injury. This study investigated whether NIM811 (N-methyl-4-isoleucine cyclosporine), an inhibitor of the mitochondrial permeability transition (MPT), attenuates cholestatic liver injury in vivo. Cholestasis was induced in mice by bile duct ligation (BDL). NIM811 was gavaged (20 mg/kg) before BDL and daily (10 mg/kg) afterward. Mitochondrial depolarization, cell death, and MPT onset were assessed by intravital confocal/multiphoton microscopy of rhodamine 123, propidium iodide, and calcein. After BDL, serum alanine aminotransferase (ALT), hepatic necrosis, and apoptosis all increased. NIM811 decreased ALT, necrosis, and apoptosis by 60 to 86%. In vehicle-treated mice at 6 h after BDL, viable hepatocytes with depolarized mitochondria were 18/high-power field (hpf), and nonviable cells were ∼1/hpf, showing that depolarization preceded necrosis. Calcein entered mitochondria after BDL, indicating MPT onset in vivo. NIM811 decreased depolarization by 72%, prevented calcein entry into mitochondria, and blocked release of cytochrome c. Hepatic tumor necrosis factor α, transforming growth factor-β1, procollagen α1(I) mRNA, α-smooth muscle actin, and Sirius red staining for collagen increased after BDL but were not different in vehicle- and NIM811-treated mice. Taken together, NIM811 decreased cholestatic necrosis and apoptosis but did not block fibrosis, indicating that the MPT plays an important role in cholestatic cell death in vivo.
Footnotes
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This study was supported, in part, by the National Institutes of Health (Grants DK70844, DK073336, DK037034, and C06 RR015455).
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The data presented here have appeared in abstract form as follows: Zhong Z, Curtin RA, Theruvath TP, Waldmeier PC, and Lemaster JJ (2006) NIM811, a mitochondrial permeability transition inhibitor, attentuates cholestatic liver injury. Gastroenterology 130:759.
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Article, publication date, and citation information can be found at http://jpet.aspetjournals.org.
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doi:10.1124/jpet.108.143578.
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ABBREVIATIONS: BA, bile acid; ROS, reactive oxygen species; PT, permeability transition; MPT, mitochondrial permeability transition; CsA, cyclosporine A; NIM811, N-methyl-4-isoleucine cyclosporine; HSC, hepatic stellate cell; BDL, bile duct ligation; ALT, alanine transaminase; Rh123, rhodamine 123; PI, propidium iodide; AM, acetoxymethyl ester; SMA, smooth muscle actin; TUNEL, terminal deoxynucleotidyltransferase dUTP nick-end labeling; TNF, tumor necrosis factor; TGF, transforming growth factor; PCR, polymerase chain reaction; HPRT, hypoxanthine phosphoribosyl-transferase; hpf, high-power field; NPC, nonparenchymal cell; CypD, cyclophilin D; BSEP, bile salt excretion pump; NTCP, Na+/taurocholate-cotransporting polypeptide.
- Received July 15, 2008.
- Accepted September 17, 2008.
- The American Society for Pharmacology and Experimental Therapeutics
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