A1 Refereed original research article in a scientific journal
Activation of Plasmacytoid Dendritic Cells in Colon-Draining Lymph Nodes during Citrobacter rodentium Infection Involves Pathogen-Sensing and Inflammatory Pathways Distinct from Conventional Dendritic Cells
Authors: Toivonen R, Kong LJ, Rasool O, Lund RJ, Lahesmaa R, Hanninen A
Publisher: AMER ASSOC IMMUNOLOGISTS
Publication year: 2016
Journal: Journal of Immunology
Journal name in source: JOURNAL OF IMMUNOLOGY
Journal acronym: J IMMUNOL
Volume: 196
Issue: 11
First page : 4750
Last page: 4759
Number of pages: 10
ISSN: 0022-1767
eISSN: 1550-6606
DOI: https://doi.org/10.4049/jimmunol.1600235
Abstract
Dendritic cells (DCs) bear the main responsibility for initiation of adaptive immune responses necessary for antimicrobial immunity. In the small intestine, afferent lymphatics convey Ags and microbial signals to mesenteric lymph nodes (LNs) to induce adaptive immune responses against microbes and food Ags derived from the small intestine. Whether the large intestine is covered by the same lymphatic system or represents its own lymphoid compartment has not been studied until very recently. We identified three small mesenteric LNs, distinct from small intestinal LNs, which drain lymph specifically from the colon, and studied DC responses to the attaching and effacing pathogen Citrobacter rodentium in these. Transcriptional profiling of conventional (CD11c(high)CD103(high)) DC and plasmacytoid (plasmacytoid DC Ag-1(high)B220(+)CD11c(int)) DC (pDC) populations during steady-state conditions revealed activity of distinct sets of genes in these two DC subsets, both in small intestinal and colon-draining LNs. C. rodentium activated DC especially in colon-draining LNs, and gene expression changed in pDC more profoundly than in conventional DC. Among the genes most upregulated in pDC were C-type lectin receptor CLEC4E, IL-1Rs (IL-1R1 and -2), proinflammatory cytokines (IL-1a and IL-6), and TLR6. Our results indicate that colon immune surveillance is distinct from that of the small intestine in terms of draining LNs, and identify pDC as active sentinels of colonic inflammation and/or microbial dysbiosis.
Dendritic cells (DCs) bear the main responsibility for initiation of adaptive immune responses necessary for antimicrobial immunity. In the small intestine, afferent lymphatics convey Ags and microbial signals to mesenteric lymph nodes (LNs) to induce adaptive immune responses against microbes and food Ags derived from the small intestine. Whether the large intestine is covered by the same lymphatic system or represents its own lymphoid compartment has not been studied until very recently. We identified three small mesenteric LNs, distinct from small intestinal LNs, which drain lymph specifically from the colon, and studied DC responses to the attaching and effacing pathogen Citrobacter rodentium in these. Transcriptional profiling of conventional (CD11c(high)CD103(high)) DC and plasmacytoid (plasmacytoid DC Ag-1(high)B220(+)CD11c(int)) DC (pDC) populations during steady-state conditions revealed activity of distinct sets of genes in these two DC subsets, both in small intestinal and colon-draining LNs. C. rodentium activated DC especially in colon-draining LNs, and gene expression changed in pDC more profoundly than in conventional DC. Among the genes most upregulated in pDC were C-type lectin receptor CLEC4E, IL-1Rs (IL-1R1 and -2), proinflammatory cytokines (IL-1a and IL-6), and TLR6. Our results indicate that colon immune surveillance is distinct from that of the small intestine in terms of draining LNs, and identify pDC as active sentinels of colonic inflammation and/or microbial dysbiosis.
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