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Leone, A., McMillian, M., Proctor, J., Kao, M., Troisi, J., Fermier, A., Varacallo, L., Taggart, P., McCarty, J., Sawant, S., Collins, A., Nie, A., Taylor, E., Lord, P. and Kelley, M. (2008) Idiosyncratic hepatotoxicity: A rat Model of Converting Oxidative Stress/Reactive Metabolites to Hepatotoxicants. Society of Toxicologic Pathology Annual Meeting (47th), Seattle, Washington, 16-20 March.

has been cited by the following article:

• TITLE: Repression of oxidative stress/reactive metabolite regulated gene expression is associated with conversion of carbamazepine into a hepatotoxicant in LPS and DSS rat models

  AUTHORS: Angelique M. Leone, Erin Saleh, S. Jim Proctor, Michael F. Kelley, L. Mark Kao, Lynn Varacallo, Peter Taggart, Jean McCarthy, Monica Singer, Michael McMillian

  KEYWORDS: Hepatotoxicity; Gene Expression; Oxidative Stress/Reactive Metabolites (OS/RM); LPS; DSS

  JOURNAL NAME: Advances in Bioscience and Biotechnology, Vol.5 No.3, February 10, 2014

  ABSTRACT: Idiosyncratic hepatotoxicity accounts for many drug failures in the clinic and is a leading cause for black-boxed and withdrawn drugs. This toxicity has proven difficult to predict preclinically, but correlates with oxidative stress/reactive metabolites (OS/RM). As noted previously for antiepileptic compounds, many drugs causing idiosyncratic adverse drug effects are detected by OS/RM gene expression responses in the rat. In the present study, two immune activation models, low dose lipopolysaccharide (1 mg/kg IV) and 5% dextran sulphate sodium (DSS) in drinking water, were examined to determine if either would convert the non-toxic idiosyncratic toxicant carbamazepine (225 mg/kg) into a rat hepatotoxicant at 24 hours. Using the low dose LPS model, about 1/3 of the carbamazepine-treated rats either showed robust ALT and AST elevations with histopathological evidence of hepatotoxicity, or died. Rats in this LPS/carbamazepine group were subdivided based on ALT values into non-responders, responders or robust responders. Whereas most carbamazepine-induced mRNAs were repressed by LPS across all rats in this group, the OS/ RM genes aflatoxin aldehyde reductase (Afar) and glutathione transferase Ya (Gstya) were repressed only in the robust responder subgroup; it is unclear whether repression of these genes contributes to or results from hepatotoxicity. The OS/RM gene microsomal epoxide hydrolase (mEphx) showed repression across all rats. NAD(P)H: menadione oxidoreductase (Nmor) is an OS/RM-responsive gene that is also induced by LPS, confounding interpretation of its changes. After pretreatment with 5% DSS at 24 hours or for 5 days, using a protocol that reportedly produces increased endotoxin absorption, carbamazepine was not converted to a hepatototoxicant in any rats. Instead, DSS produced a pronounced (2- to 6-fold) and selective potentiation of carbamazepine induction of OS/RM-responsive mRNAs. The lack of repressive effects of DSS on these mRNAs or in converting carbamazepine to a hepatotoxicant was not due to desensitization of endotoxin responses since LPS was at least as effective when administered to DSS-pretreated rats. OS/RM gene repression may contribute to development of hepatotoxicity of carbamazepine in immune activation models.