Involvement of platelet-activating factor in cytokine production and neutrophil activation after hepatic ischemia-reperfusion



Although platelet-activating factor (PAF) is implicated as an important mediator in the pathogenesis of hepatic ischemia-reperfusion (IR) injury, the precise mechanism of its action has not been studied. We examined the hypothesis that PAF may influence neutrophils by promoting the production of tumor necrosis factor α (TNF-α) and cytokine-induced neutrophil chemoattractant (CINC), a member of the interleukin-8 (IL-8) family, and may be associated with liver and lung injury during the early phase of reperfusion after total hepatic ischemia. Rats pretreated with a specific PAF receptor antagonist exhibited suppression of the increase in plasma TNF-α and CINC levels, as well as the priming of peripheral neutrophils for superoxide production after reperfusion when compared with animals pretreated with physiological saline. These effects resulted in a reduction of plasma liver enzymes and of hepatic and pulmonary neutrophil sequestration, as well as an increased survival rate. There was a strong correlation between the time course of CINC release and hepatic or pulmonary neutrophil sequestration. We concluded that PAF activates neutrophils, either directly or by promoting the production of TNF-α and CINC, and is involved in hepatic IR injury.