Cell therapy by tolerogenic dendritic cells has become an attractive therapeutic option in transplantation. We could recently show that high expression of TCAIM, formerly known as TOAG-1, in dendritic cells (DCs) is associated with stable tolerance following transplantation. Here, we investigated transcriptional control of TCAIM in murine bone marrow derived DCs (BMDCs) and human MUTZ-3 derived DCs (M3DCs). We have cloned the human TCAIM promoter to identify regulatory elements by site directed mutagenesis. In addition, we performed luciferase reporter as well as ChIP assays. Furthermore, BMDCs or M3DCs were pre-incubated with cAMP elevating drugs prior to LPS-mediated maturation. Phenotype and tolerogenic potential of DCs were investigated by qPCR, flow cytometry, CBA and MLR. Site-directed mutagenesis, reporter assays and ChIP defined TCAIM core promoter containing three CREB responsive elements. Co-transfections revealed positive regulation of promoter activity by NFATc1 and C/EBPβ. Furthermore, pre-incubation of M3DCs or BMDCs with cAMP elevating drugs leading to CREB activation resulted in high TCAIM expression, inhibited DC maturation, diminished pro-inflammatory cytokine release and induced high frequency of CD4+CD25+FoxP3+ Tregs in DC-T cell co-cultures. These results indicate that transcriptional activation of TCAIM is cAMP/CREB dependent and further amplified by NFATc1 and C/EBPβ, resulting in induction of tolerogenic potential in human M3DCs and murine BMDCs.
- Copyright © 2013 by The American Association of Immunologists, Inc.