• Dan Takeuchi, Hiroyuki Yoshidome, Atsushi Kato, Hiroshi Ito, Fumio Kimura, Hiroaki Shimizu, Masayuki Ohtsuka, Yasuhiro Morita, and Masaru Miyazaki.
• Department of General Surgery, Chiba University Graduate School of Medicine, 1-8-1 Inohana Chuo-ku, Chiba 260-0856, Japan.
• Hepatology. 2004 Mar 1;39(3):699-710.

AbstractHepatic ischemia/reperfusion injury is a clinically important problem. While the mechanisms of the initial event and subsequent neutrophil-dependent injury are somewhat understood, little is known about the regulation of endogenous hepatoprotective effects on this injury. Interleukin 12 (IL-12) plays a role in the induction of this injury, but involvement of interleukin 18 (IL-18) has not been clarified. Using a murine model of partial hepatic ischemia and subsequent reperfusion, the aim of the current study was to determine whether IL-18 is up-regulated during hepatic ischemia/reperfusion and to determine the role of endogenous IL-18 in the development and regulation of inflammatory hepatic ischemia/reperfusion injury. Hepatic IL-18 expression was up-regulated from 1 to 8 hours after reperfusion. Hepatic ischemia/reperfusion induced nuclear factor-kappaB (NF-kappaB) and activator protein 1 (AP-1) activation, as defined by electrophoretic mobility shift assay, and caused significant increases in liver neutrophil recruitment, apoptosis, hepatocellular injury, and liver edema as defined by liver myeloperoxidase content, terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate biotin nick end-labeling (TUNEL) staining, serum aminotransferase levels, and liver wet-to-dry weight ratios. In mice treated with neutralizing antibody to IL-18, ischemia/reperfusion-induced increases in CXC chemokine expression, activation of NF-kappaB and AP-1, and apoptosis were greatly reduced. Furthermore, under blockade of IL-18, anti-inflammatory cytokines such as IL-4 and IL-10 were greatly up-regulated. Signal transducer and activator of transcription 6 (STAT6) was significantly activated under blockade of IL-18. These conditions also caused significant reduction in liver neutrophil sequestration and liver injury. In conclusion, the data suggest that IL-18 is required for facilitating neutrophil-dependent hepatic ischemia/reperfusion injury through suppressing anti-inflammatory cytokine expression.

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