Effect of cold-ischemia time on C-X-C chemokine expression and neutrophil accumulation in the graft liver after orthotopic liver transplantation in rats

Abstract

The precise mechanisms leading to polymorphonuclear neutrophil (PMN) recruitment and activation in the extended cold-preserved liver after transplantation are not yet fully understood. We histologically evaluated the number of accumulated PMNs in graft livers, with varying time periods of cold ischemia (1, 6, and 24 hr in University of Wisconsin solution at 4 degrees C), after liver transplantation in rats. Intragraft expression of macrophage inflammatory protein-2 (MIP-2) and cytokine-induced neutrophil chemoattractant (CINC) mRNA, as well as immunohistochemical expression of MIP-2 and CINC in the graft liver, were investigated after reperfusion. The levels of MIP-2 and CINC in the hepatic vein, and tumor necrosis factor (TNF)-alpha, which stimulates these chemokine production, were also monitored. The number of accumulated PMNs in sinusoids significantly increased in the 24-hr cold-ischemia group within 3 hr after reperfusion, compared with the 1-hr and 6-hr groups. Serum MIP-2 levels in the 24-hr group significantly increased at 3, 6, and 12 hr after reperfusion, compared with the other groups. Intragraft MIP-2 mRNA was also up-regulated to a greater extent in the 24-hr group. Similarly, serum CINC levels in the 24-hr group significantly increased at 3 hr, compared with the 1-hr group. CINC mRNA also increased as cold-ischemia time was prolonged. Immunohistochemical staining revealed that hepatocytes were the main source of both MIP-2 and CINC protein. In addition, TNF-alpha in the hepatic vein was detected only in the 24-hr group after reperfusion. Extended cold preservation of the graft liver might up-regulate MIP-2 and CINC expression of hepatocytes, most probably through elevated TNF-alpha, and might contribute to PMN recruitment and activation after reperfusion.