Immunomodulatory effect of 5-azacytidine (5-azaC): potential role in the transplantation setting.. Homo sapiens

Cytokine genes are targets of multiple epigenetic mechanisms in T lymphocytes. 5-azacytidine (5-azaC) is a nucleoside-based DNA methyltransferases (DNMT) inhibitor which induces demethylation and gene reactivation. In the current study, we analyzed the effect of 5-azaC in T-cell function and observed that 5-azaC inhibits T-cell proliferation and activation, blocking cell cycle in G0-G1 phase and decreasing the production of proinflammatory cytokines such as TNFα and IFNγ. This effect was not due to a pro-apoptotic effect of the drug but to the down-regulation of genes involved in T-cell cycle progression and activation such as CCNG2, MTCP1, CD58, and ADK and up-regulation of genes which induce cell growth arrest, such as DCUN1D2, U2AF2, GADD45B or p53. In spite of being also up-regulated, we did not find any effect of 5-azaC on the methylation pattern of FOXP3. Finally, the administration of 5-azaC at 60 and 84 hours post-transplant prevented the development of GVHD leading to a significant increase in survival in a fully mismatched BMT mouse model. In conclusion, the current study shows the effect of 5-azaC in T-lymphocytes and illustrates its role in the allogeneic transplantation setting as an immunomodulatory drug, describing new pathways which must be explored in order to prevent graft-versus-host disease. Overall design: In order to elucidate the mechanisms involved in the effect of 5-azaC on T-cells we performed Affymetrix gene expression assays in T-cells untreated versus treated with 5-azaC at 1 μM after 2 and 4 days of culture, making a total of 12 samples (coming from time-series studies of 3 healthy individuals)