Marked Difference in Tumor Necrosis Factor-α Expression in Warm Ischemia– and Cold Ischemia–Reperfusion of the Rat Liver

Abstract

Although tumor necrosis factor-α has been implicated in liver injury after both warm ischemia– and cold ischemia–reperfusion, it is unclear whether reactivity of the liver to these stimuli is similar with regard to cytokine expression. Here we compare the effects of warm and cold ischemia on tumor necrosis factor-α expression and test the hypothesis that cold ischemia preceding warm ischemia causes overexpression of this cytokine. Rat livers were flushed out with University of Wisconsin solution and subjected to varying periods of warm ischemia, cold ischemia, or cold ischemia plus warm ischemia followed by reperfusion using a blood-free perfusion model. Tumor necrosis factor-α and interleukin-10 release into the perfusate and bile were measured by ELISA, and expression of these cytokines and that of c-fos, c-jun, and c-myc were studied by reverse-transcriptase polymerase chain reaction. We found high levels of tumor necrosis factor-α in the perfusates of livers subjected to warm ischemia–reperfusion, whereas minimal or no tumor necrosis factor-α was detected in livers subjected to cold ischemia–reperfusion or to cold ischemia plus warm ischemia–reperfusion. Reverse-transcriptase polymerase chain reaction confirmed the above findings and showed that immediate early genes were expressed in reperfused groups of livers. Measurements of cytokine release into bile showed that neither tumor necrosis factor-α nor interleukin-10 were upregulated by cold ischemia–reperfusion. The results suggest that (1) warm ischemia– and cold ischemia–reperfusion of rat liver lead to very different outcomes with regard to tumor necrosis factor-α expression and (2) cold ischemia preceding warm ischemia prevents upregulation of tumor necrosis factor-α.