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.
