Inhibition of the JAK/STAT pathway by ruxolitinib ameliorates thioacetamide-induced hepatotoxicity Mohamed E. Shaker a, * , Sara H. Hazem a , Sylvia A. Ashamallah b a Pharmacology and Toxicology Dept., Faculty of Pharmacy, Mansoura University, Mansoura 35516, Egypt b Pathology Dept., Faculty of Medicine, Mansoura University, Mansoura 35516, Egypt article info Article history: Received 15 January 2016 Received in revised form 23 July 2016 Accepted 15 August 2016 Available online 18 August 2016 Keywords: Ruxolitinib Thioacetamide JAK/STAT Oxidative stress Hepatotoxicity abstract In an attempt to explore the role of the JAK/STAT pathway in liver inflammation, we investigated the effect of intervening this pathway by ruxolitinib in thioacetamide (TAA)-induced hepatotoxicity. Ruxolitinib treatments were administered to male mice either before or after intoxication with TAA. The hepatic histopathological and serum biochemical assessment revealed that ruxolitinib pre-treatments dose- dependently reduced TAA-induced liver injury, caspase 3 cleavage and increase in number of hepatocytes positive for the pro-apoptotic Bax, as well as inflammatory cells positive for F4/80 and myeloperoxidase activity in the liver. Ruxolitinib pre-treatments also curbed TAA-induced rise in NF-kB nuclear expression and STAT3 phosphorylation. Ruxolitinib pre-treatments also lowered TAA-induced elevation of hepatic oxidative stress parameters (total nitrate/nitrite and 4-hydroxynonenal), but did not restore the hepatic antioxidant reduced glutathione. Interestingly, ruxolitinib, especially at a dose of 200 mg/kg, dampened the overproduction of pro-inflammatory cytokines (TNF-a, IL-1b, IFN-g, IL-23 and IL-17A), which coincided with boosting the release of the anti-inflammatory cytokine IL-10. Ruxolitinib when used as a post- treatment (1 and 3 h after TAA-insult) could still spare the liver from injury and might be clinically applicable. In conclusion, the multimechanistic-hepatoprotective activity of ruxolitinib can be linked to its ameliorative properties on cellular death, oxidative stress and inflammation machinery. © 2016 Elsevier Ltd. All rights reserved. 1. Introduction Hepatic diseases are a major cause of worldwide morbidity and mortality. Most types of hepatic diseases are characterized by in- flammatory processes with enhanced expression of various pro- inflammatory cytokines in the liver. One of the major pathways involved in the signal transductions of wide arrays of these cyto- kines is the Janus kinase/signal transducers and activators of transcription (JAK/STAT) cascade. The JAK/STAT pathway is a key player in many important biological processes, including broad immune and hematopoietic cell functions (Rane and Reddy, 2000). On the other hand, erratic function of this pathway is widely implicated in various types of illness, such as autoimmune diseases, hematopoietic disorders, graft rejection and inflammation, (Ghoreschi et al., 2011). JAKs comprise a group of 4 tyrosine kinases (JAK1, JAK2, JAK3 and TYK2) that selectively associate with cytokine receptor chains and transduce signaling through phosphorylating tyrosine residues on themselves and STATs (Pesu et al., 2008). STATs subsequently become dimerized and transport to the nucleus, where they acti- vate or suppress the gene transcription (Harrison, 2012). Thus, the pharmacological modulation of elements of this pathway may represent a novel treatment approach for inflammatory and immune-mediated diseases. Ruxolitinib, a novel oral JAKs 1 and 2 inhibitor, was recently approved as a revolutionary therapy for patients suffering from intermediate/high risk myelofibrosis (Mascarenhas and Hoffman, 2012). Although the efficacy of ruxolitinib in myelofibrosis is now well established, data about the effect of ruxolitinib in inflam- matory disorders, especially those occurring in the liver, are still limited. Most recently, we found that pre-treatment with rux- olitinib protected mice from carbon tetrachloride-induced hepa- totoxicity (Hazem et al., 2014). In this study, we examined whether the capability of ruxolitinib to confer hepatoprotection is also extended to thioacetamide (TAA)-induced hepatotoxicity * Corresponding author. E-mail address: mshaker2222@yahoo.com (M.E. Shaker). Contents lists available at ScienceDirect Food and Chemical Toxicology journal homepage: www.elsevier.com/locate/foodchemtox http://dx.doi.org/10.1016/j.fct.2016.08.018 0278-6915/© 2016 Elsevier Ltd. All rights reserved. Food and Chemical Toxicology 96 (2016) 290e301