ObjectiveTo explore the influence of miRNA-155/PU.1 signaling pathway blockade on bone marrow-derived dendritic cells (DCs) maturation and immune function of rat small intestinal transplantation. MethodsThe DCs were induced by adherent culture.The critical transcription factor gene PU.1 was designed and PU.1 siRNA was synthe-sized.The DCs were transfected by liposome transfection and a pair of PU.1 siRNA was screened according to the high silencing efficiency.The expressions of DCs surface markers CD80, CD86, and MHC-Ⅱamong three groups (PU.1 silent group, negative control group, and control group) were analyzed by flow cytometry.The IL-10 and IL-12p70 secretion levels in the supernatant were tested by ELISA method.The allogeneic T lymphocyte proliferation was tested by mixed lymphocyte reaction.The transfected cells were intravenously injected into the recipient rat on day 7 before intestinal transplantation.The survival conditions as well as pathological changes were observed in each group recipients. Results①The surface molecules CD80, CD86, and MHC-Ⅱin the PU.1 silent group were (27.0±5.6)%, (23.6±4.8)%, and (36.8±6.8)%, respectively; versus (74.0±9.4)%, (76.5±8.7)%, and (87.8±11.3)% in the negative control group, respectively, which were significantly lower in former and showing an in creased trend (P < 0.05).②Compared with the negative control group, IL-10 secretion level was significantly increased (P < 0.05), IL-12p70 secretion level significantly decreased (P < 0.05) in the PU.1 silent group.③The proliferation of T lymphocytes in the PU.1 silent group was significantly lower than that in the negative control group (P < 0.05).④When the transfected DCs were injected into the intestinal transplantation rats on day 7 before operation, the survival time was (14.3±3.3) d, (7.8±1.5) d, and (8.0±2.5) d in the PU.1 silent group, negative control group, and control group, respectively, which in the PU.1 silent group were significantly longer than that in the other two groups (P < 0.05), and the graft pathology showed that there were mild intestinal tissue damage, lymphocyte infiltration or villus edema in the PU.1 silent group. ConclusionmiRNA-155/PU.1 signaling pathway blockade could reduce DCs maturation and induce receptor-specific immune tolerance, which are proved both in vivo and in vitro.