CX3CR1 is critical for Salmonella-induced migration of dendritic cells into the intestinal lumen

We have demonstrated that direct antigen sampling of bacteria by intestinal dendritic cells (DCs) is accompanied by a rapid migration of CD11c+CX3CR1+MHCII+CD8alpha; CD11b-DCs into the intestinal lumen upon exposure to non-invasive δSPI1-Salmonella. Importantly, intraluminal DCs internalized Salmonella but were not able to cross the epithelium to return into tissue, thus showing that these DCs do not function as antigen-presenting cells and participate in the conventional regulation of immune responses to intestinal pathogens. Here we show that the presence of the chemokine receptor CX3CR1, that plays a vital role in DC-mediated antigen sampling and clearance in the gut, is also instrumental for the transepithelial migration of DCs. The latter observation, along with the notion that CX3CR1-deficient mice displayed higher susceptibility to Salmonella infection compared to wild type mice raises the possibility that Salmonella-induced migration of bacteria-capturing DCs into the lumen may be an important mechanism of mucosal defence and clearance. © 2010 Landes Bioscience. Antigen sampling; Cell migration; Dendritic cell; Immune exclusion; Mucosal clearance; Mucosal immunity; Salmonella