A reduced population of CD103⁺CD11b⁺ dendritic cells has a limited impact on oral Salmonella infection

CD103⁺CD11b⁺ dendritic cells (DC) are the major migratory DC subset in the small intestine lamina propria (siLP) and their survival is dependent on the transcription factor interferon regulatory factor 4 (IRF4). Mice with a DC-specific deletion of irf4 (CD11c-cre.Irf4 mice) have reduced mucosal CD103⁺CD11b⁺ DC and altered T cell differentiation to protein antigen. The influence of CD103⁺CD11b⁺ DC on oral infection with the gastrointestinal pathogen Salmonella, however, is poorly understood and is investigated here. We show that, despite being infected with Salmonella, CD11c-cre.Irf4 mice (called Cre⁺ mice) conserve the reduction in CD103⁺CD11b⁺ DC observed in naive Cre⁺ mice, particularly in the mesenteric lymph nodes (MLN) but also in the siLP at day 3 post infection. Moreover, Salmonella-infected Cre⁺ mice have a similar bacterial burden in intestinal tissues (siLP, MLN and Peyer's patches) as well as the spleen compared to infected Cre^- controls. The T cell compartment, including the frequency of IFN-γ and IL-17-producing T cells, is not altered in intestinal tissues of Salmonella-infected Cre⁺ mice relative to infected Cre^- controls. In addition, no difference between infected Cre⁺ and Cre^- mice was observed in either the concentration of IL-6 or IL-17 in whole tissue lysates of siLP, MLN or Peyer's patches or in the serum concentration of Salmonella-specific IgG and IgM. Overall the data suggest that the reduction of CD103⁺CD11b⁺ DC in Cre⁺ mice has little if any impact on Salmonella burden in infected tissues or eliciting effector functions important in host survival at later stages of the infection.