Published in:
Open Access 01-02-2008 | Research article
Indoleamine 2,3-dioxygenase-expressing dendritic cells are involved in the generation of CD4+CD25+regulatory T cells in Peyer's patches in an orally tolerized, collagen-induced arthritis mouse model
Published in: Arthritis Research & Therapy | Issue 1/2008
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Introduction
The present study was devised to understand the role of systemic indoleamine 2,3-dioxygenase (IDO) in the tolerance induction for orally tolerized mice in collagen-induced arthritis (CIA). We examined whether IDO-expressing dendritic cells (DCs) are involved in the generation of CD4+CD25+ regulatory T cells during the induction of oral tolerance in a murine CIA model.
Methods
Type II collagen was fed six times to DBA/1 mice beginning 2 weeks before immunization, and the effect on arthritis was assessed. To examine the IDO expression, the DCs of messenger RNA and protein were analyzed by RT-PCR and Flow cytometry. In addition, a proliferative response assay was also carried out to determine the suppressive effects of DCs through IDO. The ability of DCs expressing IDO to induce CD4+CD25+ T regulatory cells was examined.
Results
CD11c+ DCs in Peyer's patches from orally tolerized mice expressed a higher level of IDO than DCs from nontolerized CIA mice. IDO-expressing CD11c+ DCs were involved in the suppression of type II collagen-specific T-cell proliferation and in the downregulation of proinflammatory T helper 1 cytokine production. The suppressive effect of IDO-expressing CD11c+ DCs was mediated by Foxp3+CD4+CD25+ regulatory T cells.
Conclusion
Our data suggest that tolerogenic CD11c+ DCs are closely linked with the induction of oral tolerance through an IDO-dependent mechanism and that this pathway may provide a new therapeutic modality to treat autoimmune arthritis.