CX3CR1 cells facilitate the activation of CD4 T cells in the colonic lamina propria during antigen-driven colitis

Abstract

Dendritic cells (DCs) and macrophages populate the intestinal lamina propria to initiate immune responses required for the maintenance of intestinal homeostasis. To investigate whether CX3CR1 phagocytes communicate with CD4 Tcells during the development of transfer colitis, we established an antigen-driven colitis model induced by the adoptive transfer of DsRed OT-II cells in CX3CR1GFP/ RAG recipients challenged with Escherichia coli expressing ovalbumin (OVA) fused to a cyan fluorescent protein (CFP). After colonization of CX3CR1GFP/ RAG animals with red fluorescent E. coli pCherry-OVA, colonic CX3CR1 cells but not CD103 DCs phagocytosed E. coli pCherry-OVA. Degraded bacterial-derived antigens are transported by CD103 DCs to mesenteric lymph nodes (MLNs), where CD103 DCs prime naive Tcells. In RAG recipients reconstituted with OT II cells and gavaged with OVA-expressing E. coli, colonic CX3CR1 phagocytes are in close contact with CD4 Tcells and presented bacterial-derived antigens to CD4 T cells to activate and expand effector T cells. © 2014 Society for Mucosal Immunology.