The immunoprotection of transplant mice allograft by suppressor of cytokine signaling 1 gene-modified dendritic cells induces T cell anergy

Objective To study the regulation of high expression of suppressor of cytokine signaling 1 (SOCS1) molecule in dendritic cells (DC), and to verify the effect of DC-SOCS1 on T cell function and allografts immune protective effects in vitro and in vivo. Methods DC were modified with high affinity replication-defective adenoviral vector Ad5F35 over-expressing SOCS1. The phenotype of transduced mature DC and the function were analyzed, and the mechanism of inducing donor-specific CD4+ T cells hyporesponsiveness was explored. The mouse allogenic islet transplantation model was established, and 24 h prior to transplantation each recipient mouse was given DC cells, DC-SOCS1 cells or equal amount of phosphate buffer (PBS), named DC group, DC-SOCS1 group and control group respectively. The survival of islet grafts of transplanted recipients was observed, and on the day 7 and the rejection day post transplantation, the islet graft glucose tolerance, pathological changes, the percentage of T cell subsets in the spleen and draining lymph nodes as well as related cytokines were observed. The possible associated mechanisms of SOCS1 gene-modified mature DC mitigating immune rejection and inducing transplant tolerance in vivo were explored. Results Genetic modified Ad5F35 dramatically increased the transduction efficiency of DC compared to regular Ad. The experimental data demonstrated there was a tendency that DC overexpressing SOCS1 can induce DC low down the express of MHC and costimulatory molecules, potentiate the ability of DC-SOCS1 to induce donor specific T cell anergy in mixed lymphocytes reaction (MLR) assay. DC-SOCS1 significantly prolonged the survival time of the islet allograft with a median survival time of (37.00±2.19) days, which is significantly longer than control [(20.00±0.55) d, P=0.008] and DC group [(10.00±0.45) d, P=0.001]. Flow cytometric analysis revealed that the DC-SOCS1 dramatically reduced the population of Th1 and Tc1 [(9.92±1.57)%, P=0.027], CD4 [(17.77±2.80)%, P=0.007] and CD8 [(14.92±2.18)%, P=0.004] in spleen lymphocytes compared to control group and DC group on day 7, and a reduction of CD4 [(26.00±2.02)%, P=0.034] was observed in draining lymph nodes compared to DC group. Conclusion SOCS1 genetic modification efficiently confers mDC with low express of MHC and costimulatory molecules, and allows them to induce T cell hyporesponsiveness in vitro. The DC-SOCS1 pretreated recipients exhibit immune tolerance and prolong islet allograft survival in vivo. Key words: Dendritic cells; Gene transduction; Suppressor of cytokine signaling 1; Islet transplantation; Immune tolerance