Exosomes Derived from Immature Bone Marrow Dendritic Cells Induce Tolerogenicity of Intestinal Transplantation in Rats

Background. Dendritic cells (DCs) secrete exosomes bearing major histocompatibility complex I and II (MHC I /II) and co-stimulatory molecules, and play a critical role in immune regulation. Because immature DCs can induce T-cell tolerance in vitro and in vivo, we explored the possibility of using exosomes derived from immature DCs (imDex) for the induction of intestinal transplant tolerance in rats. Materials and Methods. ImDex were purified from F344 rat bone marrow immature DCs. The tolerizing capacities of imDex were analyzed in vitro and in vivo using a F344-to-Wistar intestinal transplantation model. Results. In the context of a moderate level of MHC class II and a low co-stimulatory level expression, imDex significantly suppressed the alloreactive T-cell response with an increase in IL-10 in vitro. In vivo injection of the lower dose (20 mu g) of donor (but not recipient) imDex can significantly prolong the survival of intestinal allografts. This effect was accompanied by a decrease in the anti-donor cellular response, with a significant increase in IL-10. The CD4+CD25+T cells percentage and FOXP3mRNA expression in splenic T-cells were also significantly increased in imDex treatment recipients at five days after transplantation. Conclusions. The results suggest that imDex can prolong the intestinal allograft survival and may be a potential strategy to facilitate induction of transplant tolerance. (C) 2011 Elsevier Inc. All rights reserved.