Pretreatment of mice with macrophage inactivators decreases acetaminophen hepatotoxicity and the formation of reactive oxygen and nitrogen species
Article first published online: 30 DEC 2003
Copyright © 1999 American Association for the Study of Liver Diseases
Volume 30, Issue 1, pages 186–195, July 1999
How to Cite
Michael, S. L., Pumford, N. R., Mayeux, P. R., Niesman, M. R. and Hinson, J. A. (1999), Pretreatment of mice with macrophage inactivators decreases acetaminophen hepatotoxicity and the formation of reactive oxygen and nitrogen species. Hepatology, 30: 186–195. doi: 10.1002/hep.510300104
- Issue published online: 30 DEC 2003
- Article first published online: 30 DEC 2003
- Manuscript Accepted: 13 APR 1999
- Manuscript Received: 16 SEP 1998
- National Institutes of Health. Grant Numbers: R01 GM-48749, R01 GM-58884 to J.A.H., DK-44716 to P.R.M.
Hepatotoxic doses of acetaminophen to mice produce not only acetaminophen-protein adducts in the centrilobular cells of the liver, but nitrotyrosine-protein adducts in the same cells, the site of the necrosis. Nitration of tyrosine occurs with peroxynitrite, a species formed by reaction of nitric oxide (NO·) with superoxide (O2·−). Because NO· and O2·− may be produced by activated Kupffer cells and/or infiltrated macrophages, we pretreated mice with the macrophage inactivators/depeleters gadolinium chloride (7 mg/kg, intravenously [iv]) or dextran sulfate (10 mg/kg, iv) 24 hours before administration of acetaminophen (300 mg/kg). Mice treated with acetaminophen plus gadolinium chloride, or acetaminophen plus dextran sulfate, had significantly less evidence of hepatotoxicity as evidenced by lower serum alanine transaminase (ALT) levels (28 ± 1 IU/L and 770 ± 240 IU/L, respectively) at 8 hours compared with acetaminophen (6,380 ± 408 IU/L). Analysis of hepatic homogenates for acetaminophen-protein adducts at 2 hours, a time of maximal covalent binding and before hepatocyte lysis, indicated that these pretreatments did not decrease covalent binding. Western blot analysis for the macrophage marker protein F4/80 in homogenates revealed not only the expected decrease by the macrophage inactivators/depleters, but also an apparent increase in acetaminophen-only–treated mice. At 8 hours nitrotyrosine-protein adducts were present in the acetaminophen-only–treated mice, but not in the acetaminophen plus gadolinium chloride–treated mice, or acetaminophen plus dextran sulfate–treated mice. High levels of heme-protein adducts, a measure of oxidative stress, were detected in livers of the 8 hour acetaminophen-only–treated mice. These data suggest that acetaminophen hepatotoxicity is mediated by an initial metabolic activation and covalent binding, and subsequent activation of macrophages to form O2·−, NO·, and peroxynitrite. Nitration of tyrosine correlates with toxicity.