Abstract
O116* Aims: The aim of the study is to probe into the protective mechanism of the combination therapy of FTY720 and fat-derived hormone adiponetin in a rat liver transplantation model using small-for-size fatty graft. Methods: A rat orthotopic liver transplantation model using 60% of liver grafts was applied. Fatty Zucker rats (240-280g) with 30% - 40% liver steatosis were used as donors. Lean Zucker rats (260-300g) were as recipients. In the FTY720 treatment group (Group 1), FTY720 (1mg/kg, IV) was administrated (1) at 20 minutes before graft harvesting in donor, (2) immediately before liver out in recipient and (3) immediately after reperfusion in recipient. In the adiponectin treatment group (Group 2), adiponectin protein from mammaline cells was given at 48 and 24 hours before graft harvesting in donor, and day1 and day 2 post-transplantation in recipient at the dose of 1.5mg/Kg by IV injection. In the combination therapy group (Group 3), adiponectin (1.5mg/kg, IV) was given at 48 and 24 hours before graft harvesting in donor, and day1 and day 2 post-transplantation in recipient in addition to FTY720. 7-day survival was compared among the treatment groups and control group (without any treatment). Liver tissues were sampled at 6, 24 and 48 hours after reperfusion for morphological examination (EM), apoptotic nuclei staining (TUNEL), energy metabolism (ATP) and intragraft gene detection for cell survival (Akt), apoptosis (Caspase) and MAPK signaling pathways by Western blot and immunostaining. Blood samples were analyzed for liver function. Fatty droplet and fat metablism were also compared. Results: FTY720 significantly improved 7-day graft survival rate to 62.5% (5/8) from 0% (0/0) of control group. Adiponectin treatment also increased 7-day survival rate remarkbly (50%, 5/10). Combined with adiponectin and FTY720, it reached to 80% (8/10). The liver steatosis by red oil staining was attenuated significantly from 30-40% to less than 10-20% at day2 post-transplantation in Group 2 and Group3. Combination therapy significantly reduced serum ALT and AST levels at 6, 24 and 48 hours after liver transplantation compared to the control or single treatment. FTY720 or adiponectin decreased serum ALT and AST only at 24 hours after transplantation compared to the control group. Combination therapy significantly increased the intragraft ATP levels compared to control group and single treatment groups. The cell survival signaling Akt pathway was significantly activated at ser473 both in FTY720 and combination groups by phosphorylation of GSK-3, Bad and FKHR. The cleaved Caspase 3, 7 and 9 were down regulated accompanied with less apoptotic nuclei. MAPK pathway was down regulated more significantly in combination groups. Hepatic ultrastructure was well maintained in combination treatment group compared to the control group with disruption of hepatic sinusoids. Conclusions: Combination therapy of FTY720 plus adiponectin rescued small-for-size fatty liver graft from injury in liver transplantation.
Published Version
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