Dexamethasone/1α-25-dihydroxyvitamin D3-treated dendritic cells suppress colitis in the SCID T-cell transfer model

Autoantigen-presenting immunomodulatory dendritic cells (DCs) that are used for adoptive transfer have been shown to be a promising therapy for a number of autoimmune diseases. We have previously demonstrated that enteroantigen-pulsed DCs treated with interleukin-10 (IL-10) can partly protect severe combined immunodeficient (SCID) mice adoptively transferred with CD4⁺ CD25⁻ T cells from the development of wasting disease and colitis. We therefore established an in vitro test that could predict the in vivo function of DCs and improve strategies for the preparation of immunomodulatory DCs in this model. Based on these in vitro findings, we here evaluate three methods for DC generation including short-term and long-term IL-10 exposure or DC exposure to dexamethasone in combination with vitamin D3 (Dex/D3). All DCs resulted in lower CD4⁺ CD25⁻ T-cell enteroantigen-specific responses in vitro, but Dex/D3 DCs had the most prominent effect on T-cell cytokine secretion. In vivo, Dex/D3 DCs most efficiently prevented weight loss and gut pathology upon CD4⁺ CD25⁻ T-cell transfer in SCID mice, although the effect on gut pathology was antigen independent. Our data in the SCID T-cell transfer model illustrate some correlation between in vitro and in vivo DC function and document that prevention of experimental inflammatory bowel disease by transfer of immunosuppressive DCs is possible.