Trovafloxacin-induced liver injury: lack in regulation of inflammation by inhibition of nucleotide release and neutrophil movement.

The fluoroquinolone trovafloxacin (TVX) is associated with a high risk of drug-induced liver injury (DILI). Although part of the liver damage by TVX+TNF relies on neutrophils, we have recently demonstrated that liver recruitment of monocytes and neutrophils is delayed by TVX. Here we show that the delayed leukocyte recruitment is caused by a combination of effects which are linked to the capacity of TVX to block the hemichannel pannexin 1. TVX inhibited find-me signal release in apoptotic HepG2 hepatocytes, decelerated freshly isolated human neutrophils toward IL-8 and f-MLF, and decreased the liver expression of ICAM-1. In blood of TVX+TNF-treated mice, we observed an accumulation of activated neutrophils despite an increased MIP-2 release by the liver. Depletion of monocytes and neutrophils caused increased serum concentrations of TNF, IL-6, and MIP-2 in TVX-treated mice as well as in mice treated with the fluoroquinolone levofloxacin, known to have a lower DILI-inducing profile. This supports the idea that early leukocyte recruitment regulates inflammation. In conclusion, disrupted regulation by leukocytes appears to constitute a fundamental step in the onset of TVX-induced liver injury, acting in concert with the capability of TVX to induce hepatocyte cell death. Interference of leukocyte-mediated regulation of inflammation represents a novel mechanism to explain the onset of DILI.