Transforming Growth Factor-beta and All-Trans Retinoic Acid Generate Ex Vivo Transgenic Regulatory T Cells With Intestinal Homing Receptors

CD4 CD25 Foxp3 regulatory T cells (Treg) mediate immunologic self-tolerance and suppress immune responses. In the gut, a subset of dendritic cells is specialized to induce Treg in a transforming growth factor- (TGF- )- and retinoic acid (RA)-dependent manner. The aim of this study was to establish if RA synergizing with TGF- induced antigen specific CD4 CD25high Foxp3 Treg portraying gut homing receptors. Splenic CD4 CD25 Foxp3 naïve T cells from DO11.10 mice were cocultured with splenic CD11c dendritic cells from Balb/c mice in the presence of TGF- , RA, and low levels of an antigenic peptide. After 5 days of culture, cells were analyzed for the expression of Foxp3 and the gut homing receptors CCR9 and 4 7. The number of Foxp3 T cells generated with TGF- and RA was at least 3 times higher than in the cultures with TGF- alone and 15 times higher than in controls without exogenous cytokines. Also, supplementation of the cultures with RA induced the expression of the intestinal homing receptors CCR9 and 4 7. Our results showed that coculture of naïve T cells with antigen-presenting cells in the presence of TGF- and RA represents a powerful approach to generate Treg with specific homing receptors.Supported by Fondecyt grants 1060834, 1060253, 1080416, Universidad Andres Bello grant DI-08-08/I and Clinica las Condes