Activation of Plasmacytoid Dendritic Cells in Colon-Draining Lymph Nodes during Citrobacter rodentium Infection Involves Pathogen-Sensing and Inflammatory This information is current as Pathways Distinct from Conventional of September 24, 2021. Dendritic Cells Raine Toivonen, Lingjia Kong, Omid Rasool, Riikka J. Lund, Riitta Lahesmaa and Arno Hänninen Downloaded from J Immunol 2016; 196:4750-4759; Prepublished online 27 April 2016; doi: 10.4049/jimmunol.1600235 http://www.jimmunol.org/content/196/11/4750 http://www.jimmunol.org/ Supplementary http://www.jimmunol.org/content/suppl/2016/04/27/jimmunol.160023 Material 5.DCSupplemental References This article cites 41 articles, 17 of which you can access for free at: http://www.jimmunol.org/content/196/11/4750.full#ref-list-1 by guest on September 24, 2021 Why The JI? Submit online. • Rapid Reviews! 30 days* from submission to initial decision • No Triage! 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The Journal of Immunology 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 Raine Toivonen,* Lingjia Kong,† Omid Rasool,† Riikka J. Lund,† Riitta Lahesmaa,† and Arno Ha¨nninen* 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 Downloaded from 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 (CD11chighCD103high) DC and plasma- cytoid (plasmacytoid DC Ag-1highB220+CD11cint) 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 http://www.jimmunol.org/ 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. The Journal of Immunology, 2016, 196: 4750–4759. onventional dendritic cells (cDCs) are sentinels of microbe- food-borne Ags and commensal bacteria (5, 6). In parallel with their and danger-associated signals in their local environment ability to induce regulatory Foxp3+ regulatory T cells under steady- and migrate from tissue to draining lymph nodes (LNs) state conditions, their importance in promoting antimicrobial C + via the lymphatic system. In the gut, the CD103 DCs are the most Th17 helper T cell responses under inflammatory conditions is predominant population of cDCs. They populate small intestinal well documented (7). by guest on September 24, 2021 lamina propria and migrate to mesenteric LNs (MLN) (1) to induce Plasmacytoid DCs (pDCs) differ from cDCs in many aspects regulatory and antimicrobial immune responses to food-borne Ags (reviewed in Ref. 8). They are mainly found in blood and secondary and commensal microbiota (2, 3). The capacity of CD103+ migra- lymphoid tissues (9, 10), but are relatively sparse in peripheral tory DCs to imprint responding CD4+ T cells with gut-homing re- tissues and mostly home in secondary lymphoid tissues directly ceptors CCR9 and integrin a4b7 (4) and to synthetize retinoic acid from circulating blood. Compared to other peripheral tissues, pDC have placed this DC subset in a central role in inducing tolerance to are numerous in intestinal lamina propria (11) of the small intestine. The ability of pDCs to capture Ags and present Ags to T cells appear to be inferior to cDCs, but their ability to sense environ- *Department of Medical Microbiology and Immunology, University of Turku, Turku mental cues and elaborate mediators of immune response never- † 20520, Finland; and Turku Centre for Biotechnology, University of Turku, Turku theless points toward an important role in T cell activation and 20520, Finland differentiation (reviewed in Ref. 12). pDCs express their unique set ORCID: 0000-0003-1016-030X (L.K.). of TLR receptors, and, in response to foreign nucleic acids, circu- Received for publication February 9, 2016. Accepted for publication March 28, 2016. lating pDCs produce large quantities of IFN-a. However, in the This work was supported by the Pa¨ivikki and Sakari Sohlberg Foundation, Academy gut, pDC appear to promote Th17 cells (13) for antimicrobial of Finland (Grants 285503 to R.T., 218057 to A.H., and Centre of Excellence in Molecular Systems Immunology and Physiology Research, 2012–2017), Finnish defense and, during steady-state conditions, to induce regulatory Diabetes Research Foundation, Maud Kuistila Memorial Fund, Turku University T cells (14). Despite these important aspects, the roles of pDC Foundation, Sigrid Juse´lius Foundation, and Finnish Microarray and Sequencing ˚ in intestinal immunity are less well characterized than those of Centre (University of Turku and Abo Akademi University and Biocenter Finland + Genome-Wide Methods Technology Platform). CD103 DCs (15). Address correspondence and reprint requests to Dr. Raine Toivonen and Dr. Arno Most of the knowledge on DCs and their roles in intestinal Ha¨nninen, Department of Medical Microbiology and Immunology, University immunity is related to the small intestine. Although colonic mucosa of Turku, Kiinamylynkatu 13, Turku 20520, Finland. E-mail addresses: raine. and lamina propria immune cells have been the focus of much toivonen@utu.fi (R.T.) and arno.hanninen@utu.fi (A.H.) research, less attention has been paid to the lymphatic drainage of The online version of this article contains supplemental material. the colon. Carter and Collins (16) used ink injections to draw a Abbreviations used in this article: cDC, conventional dendritic cell; coMLN, colon- draining MLN; DC, dendritic cell; DEG, differentially expressed gene; FDR, false sketch on the lymph drainage from different parts of the intestine discovery rate; FITC-Dx, FITC-labeled dextran; ILN, ileac LN; IRF, IFN regulatory already in 1974 and proposed that lymph from colon drains to LNs factor; LN, lymph node; MLN, mesenteric LN; pDC, plasmacytoid DC; PDCA-1, distinct from the main MLN. More recently, Van den Broeck et al. pDC Ag-1; siMLN, small intestine–draining MLN. (17) illustrated lymph drainage from the intestine using modern Copyright Ó 2016 by The American Association of Immunologists, Inc. 0022-1767/16/$30.00 imaging techniques and confirmed the distinction between lymphatics www.jimmunol.org/cgi/doi/10.4049/jimmunol.1600235 The Journal of Immunology 4751 of the small intestine and colon. Despite this, no data were available identified as CD11c (PE-conjugated clone N418; BioLegend) and CD103 to evaluate if immune responses in the small intestine and colon in- (allophycocyanin-conjugated clone 2E7; BioLegend) double-positive volve anatomically distinct lymphoid structures and cell types. This cells. Both populations were further characterized for expression of CD11c (FITC-conjugated clone N418; BioLegend), CD11b (FITC-conjugated problem was tackled quite recently by Houston et al. (18), who used clone M1/70; BD Pharmingen), F4/80 (allophycocyanin-conjugated clone photoconvertible reporter techniques and multicolor flow cytometry BM8; BioLegend), Siglec-H (PerCP/Cy5.5-conjugated clone 551; Bio- to document DC accumulation from the colon and small intestine Legend), Gr1 (Alexa 488–conjugated clone RB6-8C5; eBioscience), and into their respective draining LNs. They identified three novel colon- CD8a (FITC-conjugated, catalog number 22150083; ImmunoTools). Acti- vation of these populations were evaluated by abundance of CD80 (FITC- draining LNs distinct from the main MLN draining small intestine. + conjugated clone 16-10A1; eBioscience) and CD86 (FITC-conjugated clone The unique phenotypes of their CD103 DC subsets and T cells and GL1; eBioscience). T-lymphocytes were analyzed for IFN-g and IL-17A the inability of CD103+DCs in these LNs to prime T cells in response production. To analyze cytokine production, harvested cells were stimu- to small-intestinal and oral