Gene transfer of huCTLA4-Ig to inhibit the acute rejection of liver allograft in rats

To observe the effect of gene transfer of huCTLA4-Ig to inhibit the acute rejection of liver allograft in rats.Methods With AdEasy vector system,the recombinant adenovirus containing huCTLA4-Ig gene was constructed.Using ex vivo gene transfer technique,exogenous gene was introduced to the liver graft during cold preservation and expressed locally in the graft.The effect of inhibition of acute rejection and inducing liver graft tolerance was observed.Results No recipients in group A (without any treatment,n=5) or group B (treated with Ad-GFP,n=4) died within 3 weeks after transplantation and severe acute rejection (massive periportal infiltration,endothelilitis,damage to biliary epithelium and severe tissue destruction) was confirmed pathologically in the graft.In contrast,all recipients in group C (treated with Ad-huCTLA4-Ig,n=5) achieved long-term liver allograft survival (>150 days).Histological examination of Ad-huCTLA4-Ig transduced allografts demonstrated a mild to moderate periportal inflammation and mild injury to liver graft on day 8 posttransplant.A mild mononuclear infiltration was observed;however,there was complete preservation of the bild ducts and no evidence of vascular injury on day 150 posttransplant.The mean IL-2 concentration in serum was (362.09±45.84) ng/L at day 1 pretransplant.In control animals (groups A and B),serum IL-2 concentration was elevated to a high level within 7 days posttransplant,which was about 1.5 to 2.5 times as much as that before transplant.In contrast,in huCTLA4-Ig-treated animals (groups C),IL-2 concentration in serum was maintained at a relative low level,which was near or less than that before transplant (P<0.01).Conclusion Using ex vivo gene transfer technique,huCTLA4-Ig gene can be introduced to the liver graft during cold preservation.The modified graft can express and excrete immunoregulatory protein locally,which can suppress acute alloimmune response and is responsible for prolongation of graft survival without using routine immunosuppressive drugs.These findings provide some experimental evidence that gene delivery of sequences encoding immunoregulatory proteins can be applied to clinical liver transplantation for inhibiting the acute alloimmune response and achieving graft tolerance.7 refs,2 tabs.

Effect of Emodin in Suppressing Acute Rejection Following Liver Allograft Transplantation in Rats

Objective：To investigate the mechanism of action of emodin for suppressing acute allograft rejection in a rat model of liver transplantation.Methods：Brown Norway（BW） recipient rats of orthotopic liver transplantation（OLT） were divided into three groups,Group A receiving isografting（with BW rats as donor）, Group B receiving allografting（with Lewis rats as donor）,Group C receiving allografting and emodin treatment （50 mg/kg daily）.They were sacrificed on day 7 of post-transplantation,and their hepatic histology,plasma cytokine levels,and T-cell subset expression were detected.Results：Compared with those in Group A,rats in Group B exhibited severe allograft rejection with a rejection activity index（RAI） of 7.67±0.98,extensive hepatocellular apoptosis with an apoptosis index（Al） of 35.83±2.32,and elevated plasma levels of interleukin-2 （IL-2）,interleukin-10（IL-10）,tumor necrosis factor-α（TNF-α）,CD4^＋ and CD4^＋/CD8^＋ ratio.However,recipients in Group C showed a decrease in histological grade of rejection and hepatocellular apoptosis,as well as a decrease in plasma levels of IL-2,TNF-α,CD4^＋ and CD4^＋/CD8^＋ ratio,but elevated levels of IL-10 as compared with the allograft group.Conclusion：Post-OLT acute rejection could be attenuated by emodin,its mechanism of action may be associated with protecting hepatocytes from apoptosis,polarizing the Th 1 paradigm to Th2,and inhibiting the proliferation of CD4^＋ T cell in plasma.