Mitochondrial GSH determines the toxic or therapeutic potential of superoxide scavenging in steatohepatitis.

Abstract

BACKGROUND & AIMS:

Steatohepatitis (SH) is associated with mitochondrial dysfunction and excessive production of superoxide, which can then be converted into H(2)O(2) by SOD2. Since mitochondrial GSH (mGSH) plays a critical role in H(2)O(2) reduction, we explored the interplay between superoxide, H(2)O(2), and mGSH in nutritional and genetic models of SH, which exhibit mGSH depletion.

METHODS:

We used isolated mitochondria and primary hepatocytes, as well as in vivo SH models showing mGSH depletion to test the consequences of superoxide scavenging.

RESULTS:

In isolated mitochondria and primary hepatocytes, superoxide scavenging by SOD mimetics or purified SOD decreased superoxide and peroxynitrite generation but increased H(2)O(2) following mGSH depletion, despite mitochondrial peroxiredoxin/thioredoxin defense. Selective mGSH depletion sensitized hepatocytes to cell death induced by SOD mimetics, and this was prevented by RIP1 kinase inhibition with necrostatin-1 or GSH repletion with GSH ethyl ester (GSHee). Mice fed the methionine-choline deficient (MCD) diet or MAT1A(-/-) mice exhibited reduced SOD2 activity; in vivo treatment with SOD mimetics increased liver damage, inflammation, and fibrosis, despite a decreased superoxide and 3-nitrotyrosine immunoreactivity, effects that were ameliorated by mGSH replenishment with GSHee, but not NAC. As a proof-of-principle of the detrimental role of superoxide scavenging when mGSH was depleted transgenic mice overexpressing SOD2 exhibited enhanced susceptibility to MCD-mediated SH.

CONCLUSIONS:

These findings underscore a critical role for mGSH in the therapeutic potential of superoxide scavenging in SH, and suggest that the combined approach of superoxide scavenging with mGSH replenishment may be important in SH.

• Authors: Claudia von Montfort, Núria Matias, Anna Fernandez, Raquel Fucho, Laura Conde de la Rosa, Maria Luz Martinez-Chantar, José M Mato, Keigo Machida, Hidekazu Tsukamoto, Michael P Murphy, Abdellah Mansouri, Neil Kaplowitz, Carmen Garcia-Ruiz, Jose C Fernandez-Checa
• Journal: Journal of hepatology (J Hepatol) Vol. 57 Issue 4 Pg. 852-9 (Oct 2012) ISSN: 1600-0641 [Electronic] Netherlands
• PMID: 22687340 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, Non-P.H.S.)
• Copyright: Copyright © 2012 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.

Chemical References

• Free Radical Scavengers
• Metalloporphyrins
• Pentanoic Acids
• Prdx3 protein, mouse
• Reactive Oxygen Species
• Txn2 protein, mouse
• manganese(III)-tetrakis(4-benzoic acid)porphyrin
• Superoxides
• 3-hydroxy-4-pentenoic acid
• Thioredoxins
• Antimycin A
• Methionine
• Hydrogen Peroxide
• Peroxiredoxin III
• Superoxide Dismutase
• superoxide dismutase 2
• Mat1a protein, mouse
• Methionine Adenosyltransferase
• Alanine Transaminase
• Glutathione

Topics

• Alanine Transaminase (blood)
• Animals
• Antimycin A (pharmacology)
• Apoptosis
• Choline Deficiency (complications)
• Diet
• Disease Models, Animal
• Fatty Liver (blood, enzymology, metabolism)
• Free Radical Scavengers (pharmacology)
• Glutathione (metabolism)
• Hepatocytes (enzymology, metabolism)
• Hydrogen Peroxide (metabolism)
• Male
• Metalloporphyrins (pharmacology)
• Methionine (deficiency)
• Methionine Adenosyltransferase (genetics)
• Mice
• Mice, Inbred C57BL
• Mice, Knockout
• Mice, Transgenic
• Mitochondria, Liver (enzymology, metabolism)
• Oxidation-Reduction (drug effects)
• Pentanoic Acids (pharmacology)
• Peroxiredoxin III (metabolism)
• Primary Cell Culture
• Reactive Oxygen Species (metabolism)
• Superoxide Dismutase (genetics, metabolism)
• Superoxides (metabolism)
• Thioredoxins (metabolism)