The inhibitory effect of donor-derived DCs highly expressing functional indoleamine 2,3-dioxygenase on acute rejection in mice small bowel transplantation

Abstract

Objective To investigate the indolearnine 2,3-dioxygenase （IDO） expression of murine splenic dentritic cells （DCs） with or without interferon-γ （IFN-γ） induction and the inhibitory effect of donor-derived DCs highly expressing functional IDO on acute rejection in mice small bowel transplantation （SBT）. Methods DCs were isolated from murine spleen and cultured. The phenotypes of DCs were determined by flow cytometry. The IDO expression level and activity of DCs with or without IFN-γ induction were investigated by SQRT-PCR, Western blot and capillary electrophoresis. The alterations in stimulating ability to allogenic T lymphocyte proliferation through DCs with/without IFN-γ induction were observed by single mixed lymphocyte culture. Heterotopic SBT models were established （C57BL/6→BalB/c） and the following groups were set up, including group without treatment,group treated with induced DCs [donor-derived splenic DCs （2 ×10^6） induced by IFN-γ were preoperatively intravenously injected to recipient] and group treated with DCs [donor-derived splenic DCs （2× 10^6） without IFN-γ induction were preoperatively intravenously injected to recipient]. The survivals of grafts were observed. On the post-operation day （POD） 6, grafts were individually collected for pathological examination. Results The expression level of IDO mRNA and protein in murine splenic DCs as well as the kynurenine concentration of splenic DCs supernatants （ 1.05 ± 0. 05,1.40 ± 0. 17 and 43. 31 ± 0. 48μmol/L respectively） were correspondingly increased by IFN-γ induction （ 1.23 ± 0. 02,2. 74 ±0. 01 and 76. 52 ± 0. 44μmol/L respectively）. The stimulating ability to allogenic T lymphocyte proliferation of splenic DCs was significantly was reduced with IFN-γ induction but enhanced by application of specific inhibitor 1-methyl-tryptophan （1-MT）. The graft survival in the group treated with induced DCs （median 12 days） was significantly longer （P〈0. 01） than that in the group treated with DCs （7. 5 days） and the group without treatment （6 days）. The pathological grades in the group treated with induced DCs （subtle） were significantly lowered as compared with those in the group treated with DCs （moderate） and the group without treatment （severe） （P〈0.05）. Conclusions Murine splenic DCs had the ability of functional IDO expression. The high expression of functional IDO from splenic DCs was due to IFN-γ induction and made stimulating ability of splenic DC to allogenic T cells proliferation lower. Pre-operative medication with donor-derived DCs highly expressing functional IDO may inhibit rejection in mice SBT. Key words: Dioxygenases; Dendritic cells; Small bowel transplantation; Graft rejection; Mice