Submitted on September 28, 2005
Accepted on March 21, 2006
ANIT toxicity toward mouse hepatocytes in vivo is mediated primarily by neutrophils via CD18
Pratima Kodali1, Ping Wu2, Parshawn A Lahiji3, Eric J Brown2, and Jacquelyn J Maher4*
1 Pediatrics, University of California, San Francisco, San Francisco, California, United States
2 Medicine, University of California, San Francisco, San Francisco, California, United States
3 Medicine, University of California, San Francisco, San Francisco, California, United States; Liver Center, University of California, San Francisco, San Francisco, California, United States
4 Liver Center, University of California, San Francisco, San Francisco, California, United States; Medicine, University of California, San Francisco, San Francisco, California, United States
* To whom correspondence should be addressed. E-mail: jmaher{at}medsfgh.ucsf.edu.
-Naphthylisothiocyanate (ANIT) is a hepatotoxicant that causes acute cholestatic hepatitis with infiltration of neutrophils around bile ducts and necrotic hepatocytes. The objective of this study was to determine whether the 
2-integrin CD18, which plays an important role in leukocyte invasion and cytotoxicity, contributes to ANIT-induced hepatic inflammation and liver injury. Mice with varying levels of leukocyte CD18 expression were treated with ANIT and monitored for hepatic neutrophil influx and liver injury over 48 h. Mice that were partially deficient in CD18 (30% of normal levels) developed periportal inflammation and widespread hepatic necrosis after ANIT treatment in a pattern identical to that in wild-type mice. In contrast, mice that completely lack CD18 (CD18-null) were resistant to ANIT toxicity. 48 h after ANIT, CD18-null mice displayed 60% lower serum ALT levels and 75% less hepatic necrosis by morphometry than wild-type mice. This was true despite evidence that ANIT still provoked hepatic neutrophil influx in CD18-null mice. Wild-type mice could also be protected from ANIT-induced hepatocellular necrosis, by depleting the animals of neutrophils. Notably, neither CD18-null mice nor neutrophil-depleted wild-type mice exhibited any attenuation of bile duct injury or cholestasis due to ANIT. We conclude from these experiments that neutrophils invade ANIT-treated livers in a CD18-independent fashion but utilize CD18 to induce hepatocellular cytotoxicity. The results emphasize that neutrophil-mediated amplification of ANIT-induced liver injury is directed toward hepatocytes rather than cholangiocytes. In fact, the data indicate that the majority of ANIT toxicity toward hepatocytes in vivo is neutrophil-driven.
