title: Nramp1 expression by dendritic cells modulates inflammatory responses during Salmonella Typhimurium infection.
abstract: Host resistance against Salmonella enterica serovar Typhimurium (S. Typhimurium) is mediated by natural resistance-associated macrophage protein 1 (Nramp1/Slc11a1). Nramp1 is critical to host defence, as mice lacking Nramp1 fail to control bacterial replication and succumb to low doses of S. Typhimurium. Despite this crucial role, the mechanisms underlying Nramp1's protective effects are unclear. Dendritic cells (DCs) that sample the intestinal lumen are among the first cells encountered by S. Typhimurium following oral infection and act as a conduit for S. Typhimurium to cross the intestinal epithelial barrier. We report that DCs, including intestinal, splenic and bone marrow-derived DCs (BMDCs), express Nramp1 protein. In the small intestine, Nramp1 expression is greater in a subset of DCs (CD11c(+)CD103(-)) characterized by the elevated expression of pro-inflammatory cytokines in response to bacterial products. While Nramp1 expression did not affect S. Typhimurium replication in BMDCs, infected Nramp1+/+ BMDCs and intestinal CD11c(+)CD103(-) DCs secreted more inflammatory cytokines (IL-6, IL-12 and TNF-alpha) than Nramp1-/-, suggesting that Nramp1 expression may promote a more rapid inflammatory response following infection. Collectively, these findings reveal a new role for DCs and Nramp1 in modulating the host inflammatory response to S. Typhimurium.
authors.affiliation: Michael Smith Laboratories, University of British Columbia, Vancouver, BC, V6T 1Z3, Canada.
authors.forename: Yanet
authors.initials: Y
authors.lastname: Valdez
authors.forename: Gretchen E
authors.initials: GE
authors.lastname: Diehl
authors.forename: Bruce A
authors.initials: BA
authors.lastname: Vallance
authors.forename: Guntram A
authors.initials: GA
authors.lastname: Grassl
authors.forename: Julian A
authors.initials: JA
authors.lastname: Guttman
authors.forename: Nat F
authors.initials: NF
authors.lastname: Brown
authors.forename: Carrie M
authors.initials: CM
authors.lastname: Rosenberger
authors.forename: Dan R
authors.initials: DR
authors.lastname: Littman
authors.forename: Philippe
authors.initials: P
authors.lastname: Gros
authors.forename: B Brett
authors.initials: BB
authors.lastname: Finlay
mesh_terms: D000818:Animals; D027682:Cation Transport Proteins / Q000276:immunology*; D016207:Cytokines / Q000276:immunology; D003713:Dendritic Cells / Q000276:immunology*; D007421:Intestine, Small / Q000382:microbiology; D051379:Mice; D009092:Mucous Membrane / Q000276:immunology; D012481:Salmonella Infections, Animal / Q000276:immunology*; D012486:Salmonella typhimurium / Q000276:immunology*; D000099173:Natural Resistance-associated Macrophage Protein 1
chemical_list: D027682:Cation Transport Proteins; D016207:Cytokines; D000099173:Natural Resistance-associated Macrophage Protein 1