| Dendritic cells (DCs) represent a heterogeneous set of antigen presenting cells linking the innate and adaptive immune systems. DCs are referred to as professional antigen presenting cells (APCs) with regards to their ability to activate naive T cells. In this study, the role that DCs play in the pathogenesis of Type 1 Diabetes (T1D) was initially examined. We utilized an experimental model that allowed for the generation of bone marrow derived-dendritic cells (BM-DC) subsets that exhibit either a DC type 1 (DC1) or DC2 phenotype. We define DC1 as cells capable of producing high levels of IL-12 and inducing naive CD4+ T cell differentiation into T helper 1 (Th1) cells while DC2 are cells that produce low levels of IL-12 and induce Th2 cell differentiation. During the course of this study we also utilized several toll-like receptor (TLR) ligands to activate DC function. In addition, we tracked the migration of DCs in vivo utilizing a novel perfluoropolyether (PFPE) contrasting agent in conjunction with a modified magnetic resonance imaging (MRI) instrument. With this methodology we tested the hypothesis that NOD DCs were predisposed to adopt a DC1 phenotype that contributed to the pathogenesis of T1D. The results from our experiments show that NOD BM-DCs induced into a DC1 or DC2 functional phenotype exhibit no significant intrinsic differences in their production of IL-10 or IL-12, in comparison to wild type mice. Additionally, NOD BM-DCs expressed similar levels of CD80, CD86, CD40, and MHC class II in comparison to wild type BM-DC. Our analysis did show that the production by BM-DCs of IL-10, induced by CpG ODN, is negatively regulated by IFN-gamma. The suppressed production of IL-10 may have implications for the development of T helper cell type 1 (Th1) and Th2 cells. Altogether our study has shown that, (1) NOD BM-DCs are not intrinsically skewed towards a DC1 phenotype, (2) IFN-gamma negatively regulates the production of IL-10 in BM-DCs, and (3) NOD BM-DCs can be successfully imaged in vivo using a novel PFPE labeling/MRI detection technique. |
