Research On Inhibitory Effects Of IDO-expressing Dendritic Cells And 3-HAA On Acute Rejection Of Mice Small Bowel Transplantation

This experiment is aiming at studying the effect and mechanism of indoleamine 2,3-dioxygenase(IDO) on suppressing immune rejection of small bowel transplantation in mice. Dendritic cells highly expressing IDO(IDO+DC) were obtained by transfecting IDO gene sequence into DC from donor mice. IDO+DC and 3-hydroxyanthranilic acid(3-HAA) were used to mixed with T lymphocyte and infused into recipient mice, by which we can explore the suppressive mechanism of IDO on suppressing immune reaction of small bowel transplantation in mice.Objective To study the suppressive mechanism of IDO+DC and 3-HAA on small bowel transplantation in mice. Method Adenovirus vector containing IDO gene sequence was prepared to infect DC of donor(C57BL/6 mice) to acquire IDO+DC. CD4+ T lymphocytes were obtained from spleen of recipient(BALB/c) mice. Then CD4+ T cells were mixed with 3-HAA, IDO+DC or combination of IDO+DC and 3-HAA. Situations of T cell proliferation were measured by MTS assay. T cell apoptosis and the proportion of Treg were detected by FCM. ELISA was used in detection of cytokine changes in the mixed cell culture medium. IDO+DC or 3-HAA was infused into receptor mice after small bowel transplantation. Changes of survival time, histopathology of transplanted intestine, Treg subset ratio in spleen and cytokines in blood in each group mice were compared. Result In vitro, the proliferation of CD4+ T cells was obviously suppressed by IDO+DC and 3-HAA. T cell apoptosis and the proportion of Treg both increased in IDO+DC or 3-HAA group. IFN-,TGF-,IL-2and IL-10 in culture supernatant of IDO+DC or 3-HAA treated cells all increased in different levels. In vivo, both IDO+DC and 3-HAA could increase the graft survival time, reducing intestinal transplantation tissue damage and raise Treg subsets. The effect of the two factors can stack. Conclusion Effect of combined administration of IDO+DC and 3-HAA to CD4+ T cells was better than IDO+DC or 3-HAA alone. By direct pathway to inhibit T cell proliferation and induce apoptosis of T cells, along with the indirect pathway to induce Treg, IDO could exert immunosuppressive effects and suppress rejection of mice small bowel transplantation.