Role Of IDO Expression Of Kupffer Cells Induce Immune Tolerance After Orthotopic Rat Liver Transplantation

Objective:To detect the level of expression of Indoleamine 2,3-dioxygenase(IDO) of Kupffer Cells(KCs) in the allografts of rat orthotopic liver transplantation(LT) of immune tolerance model and acute immune reject model, then investigate the relationship of expression of IDO in KCs and the immune tolerance after LT.Methods:(1) BN to Lewis and Lewis to BN liver transplantation were performed using modified Kamada two-cuff method. Survival rate and general condition of recipients were observed after transplantation. Every three survival rats were sacrificed at days 1,3,5 and 7 post-transplantation. (2)The pathohistological change of grafts was observed by light microscope and plasma levels of alanine aminotransferase(ALT), aspartase mainotransferase(AST) and total bilirubin (TBIL) were measured with an automatic biochemical analyser. (3)IDO expression in the allograft was evaluated by immunohistochemistry staining. (4) KCs were isolated from the graft on day1,3,5,7 after LT. Changes of IDO mRNA and protein expression were determined by real-time PCR and Western bolt analysis, respectively.Results:(1) Models of BN to Lewis and Lewis to BN LT were successfully established. Without using any immunosuppressive therapy, acute rejection was observed in Lewis→BN group on day 3 after transplantation and typical characteristic reaction appeared at day 5-7, while it was not observed in BN→Lewis group.(2) Accordingly, plasma levels of ALT, AST and TBIL were sharply increased in Lewis→BN group(963.43±64.21U/L,742.46±52.71U/L,88.72±13.04μmol/L), while they were gradually decreased to normal in BN→Lewis group (P<0.05). (3)After transplantation IDO had no obvious expression in the two groups on day 1. But it elevated on day 3, and kept strong positive on day 5-7 in the BN→Lewis group, while it kept week-positive in Lewis→BN group almost all the time after LT (P<0.05). (4) The results of real-time PCR and Western blot assay indicated that the level of mRNA expression and protein expression of IDO on KCs in BN→Lewis group was significantly higher than that in the Lewis→BN group (P<0.05).Conclusion:(1) Expression of IDO in graft was quite differently between the two groups. Models of immune tolerance groups has more significantly IDO expression level than that in models of immune reject groups. (2) Significant difference has been found in the IDO expression of KCs between the immune tolerance and rejection grafts. KCs with high expression of IDO in immune tolerance grafts, while reject grafts were low. These results indicated that IDO may play a important role in the immune tolerance in liver transplantation.