MECHANISM/S OF ALCOHOL-INDUCED LIVER GRAFT FAILURE

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Liver transplantation has become an increasingly accepted therapy worldwide for patients with irreversible liver disease. Tragically, however, many children and adults die while waiting for a donor organ. One critical problem in liver transplantation is that fatty livers resulting from alcohol consumption fail when used a donor organs. Because the source of liver grafts is largely brain-dead victims of accidents heavily involving alcohol, the relationship between alcohol, fatty liver, and graft failure following transplantation urgently needs to be understood if the donor pool of usable organs is to be expanded. Therefore, the goals of this project are to identify and clarify mechanisms involved in the failure of fatty livers and to develop strategies to prevent graft failure following transplantation. We are uniquely positioned to perform this research since our laboratories have extensive experience with rodent liver transplantation. For these studies, we plan to build on recent exciting findings obtained during the first cycle of NIAAA support: namely, that fatty livers from alcohol-treated rat produce SOD/catalase- insensitive free radicals in the early minutes following transplantation and that white cell adhesion also occurs very early and to a much greater extent in livers from alcohol-treated rats. For these studies we will use our new clinically relevant rodent model of graft failure following transplantation of fatty liver developed by us. Our first goal will be to test the hypothesis that SOD/catalase-insensitive free radicals are derive from lipids. Control and ethanol-treated rats will be transplanted, lipid hydroperoxides will be measured and free radicals will be trapped postoperatively using the spin-trapping technique and quantitated using EPR spectroscopy. We expect that lipid hydroperoxides will be detected and subsequently diminished by GSH monoesters. Second adhering white cells will be isolated postoperatively and specific call types responsible for free radical production will be identified. Oxygen-centered free radicals, which could produce lipid radicals will be identified using the spin trap DMPO. Next, we will test the hypothesis that early oxidant damage to the endothelium and activation of Kupffer cells leads to expression of adhesion molecules (e.g., ICAM-I and selectins) which are responsible for white cell adhesion. Specifically, we will determine the post-operative time course of adhesion molecule expression immunohistochemically. Next, we will determine if white cells adhere to endothelium, Kupffer cells, and/or Ito cells by video and electron microscopy. The perfused liver will be used to evaluate the time course of postoperative damage to endothelium and activation of Kupffer cells with hyaluronic acid and carbon uptake, respectively. The third goal will be to evaluate the hypothesis that free radical production and/or white cell adhesion is causally responsible for failure of grafts from alcohol-exposed rats. Accordingly, we will develop strategies to decrease white cell sticking (e.g., anti-ICAM-1, Sialyl Lewis[X]) and to reduce free radicals (e.g., GSH monoester) and evaluate their effects on long-term survival of fatty grafts. Information gained from these studies will allow us to develop specific mechanism-based procedures to prevent failure of fatty livers. This information will ultimately increase the pool of usable liver grafts, decrease the need for retransplantation surgery and minimize postoperative complications.