identification of an innate t helper type 17 response to intestinal … · 17 response is a crucial...

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Identification of an innate T helper type 17 response to intestinal bacterial

pathogens

Article in Nature Medicine · June 2011

DOI: 10.1038/nm.2391 · Source: PubMed

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Stephen Rubino

Brigham and Women's Hospital and Harvard Medical School

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Joao G Magalhaes

Enterome Bioscience


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Cathy Streutker

University of Toronto


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Lionel Le Bourhis

French Institute of Health and Medical Research


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https://www.researchgate.net/publication/51212992_Identification_of_an_innate_T_helper_type_17_response_to_intestinal_bacterial_pathogens?enrichId=rgreq-886865cd06a9010c1cbe6e0c52aeb4d9-XXX&enrichSource=Y292ZXJQYWdlOzUxMjEyOTkyO0FTOjk4NTQ4ODY3NjY1OTI5QDE0MDA1MDcyOTAwMzA%3D&el=1_x_2&_esc=publicationCoverPdfhttps://www.researchgate.net/publication/51212992_Identification_of_an_innate_T_helper_type_17_response_to_intestinal_bacterial_pathogens?enrichId=rgreq-886865cd06a9010c1cbe6e0c52aeb4d9-XXX&enrichSource=Y292ZXJQYWdlOzUxMjEyOTkyO0FTOjk4NTQ4ODY3NjY1OTI5QDE0MDA1MDcyOTAwMzA%3D&el=1_x_3&_esc=publicationCoverPdfhttps://www.researchgate.net/project/Dendritic-cell-maturation?enrichId=rgreq-886865cd06a9010c1cbe6e0c52aeb4d9-XXX&enrichSource=Y292ZXJQYWdlOzUxMjEyOTkyO0FTOjk4NTQ4ODY3NjY1OTI5QDE0MDA1MDcyOTAwMzA%3D&el=1_x_9&_esc=publicationCoverPdfhttps://www.researchgate.net/project/Involvement-of-gd-T-cells-in-the-humoral-immune-response?enrichId=rgreq-886865cd06a9010c1cbe6e0c52aeb4d9-XXX&enrichSource=Y292ZXJQYWdlOzUxMjEyOTkyO0FTOjk4NTQ4ODY3NjY1OTI5QDE0MDA1MDcyOTAwMzA%3D&el=1_x_9&_esc=publicationCoverPdfhttps://www.researchgate.net/?enrichId=rgreq-886865cd06a9010c1cbe6e0c52aeb4d9-XXX&enrichSource=Y292ZXJQYWdlOzUxMjEyOTkyO0FTOjk4NTQ4ODY3NjY1OTI5QDE0MDA1MDcyOTAwMzA%3D&el=1_x_1&_esc=publicationCoverPdfhttps://www.researchgate.net/profile/Stephen-Rubino?enrichId=rgreq-886865cd06a9010c1cbe6e0c52aeb4d9-XXX&enrichSource=Y292ZXJQYWdlOzUxMjEyOTkyO0FTOjk4NTQ4ODY3NjY1OTI5QDE0MDA1MDcyOTAwMzA%3D&el=1_x_4&_esc=publicationCoverPdfhttps://www.researchgate.net/profile/Stephen-Rubino?enrichId=rgreq-886865cd06a9010c1cbe6e0c52aeb4d9-XXX&enrichSource=Y292ZXJQYWdlOzUxMjEyOTkyO0FTOjk4NTQ4ODY3NjY1OTI5QDE0MDA1MDcyOTAwMzA%3D&el=1_x_5&_esc=publicationCoverPdfhttps://www.researchgate.net/profile/Stephen-Rubino?enrichId=rgreq-886865cd06a9010c1cbe6e0c52aeb4d9-XXX&enrichSource=Y292ZXJQYWdlOzUxMjEyOTkyO0FTOjk4NTQ4ODY3NjY1OTI5QDE0MDA1MDcyOTAwMzA%3D&el=1_x_7&_esc=publicationCoverPdfhttps://www.researchgate.net/profile/Joao-Magalhaes-5?enrichId=rgreq-886865cd06a9010c1cbe6e0c52aeb4d9-XXX&enrichSource=Y292ZXJQYWdlOzUxMjEyOTkyO0FTOjk4NTQ4ODY3NjY1OTI5QDE0MDA1MDcyOTAwMzA%3D&el=1_x_4&_esc=publicationCoverPdfhttps://www.researchgate.net/profile/Joao-Magalhaes-5?enrichId=rgreq-886865cd06a9010c1cbe6e0c52aeb4d9-XXX&enrichSource=Y292ZXJQYWdlOzUxMjEyOTkyO0FTOjk4NTQ4ODY3NjY1OTI5QDE0MDA1MDcyOTAwMzA%3D&el=1_x_5&_esc=publicationCoverPdfhttps://www.researchgate.net/institution/Enterome_Bioscience?enrichId=rgreq-886865cd06a9010c1cbe6e0c52aeb4d9-XXX&enrichSource=Y292ZXJQYWdlOzUxMjEyOTkyO0FTOjk4NTQ4ODY3NjY1OTI5QDE0MDA1MDcyOTAwMzA%3D&el=1_x_6&_esc=publicationCoverPdfhttps://www.researchgate.net/profile/Joao-Magalhaes-5?enrichId=rgreq-886865cd06a9010c1cbe6e0c52aeb4d9-XXX&enrichSource=Y292ZXJQYWdlOzUxMjEyOTkyO0FTOjk4NTQ4ODY3NjY1OTI5QDE0MDA1MDcyOTAwMzA%3D&el=1_x_7&_esc=publicationCoverPdfhttps://www.researchgate.net/profile/Cathy-Streutker?enrichId=rgreq-886865cd06a9010c1cbe6e0c52aeb4d9-XXX&enrichSource=Y292ZXJQYWdlOzUxMjEyOTkyO0FTOjk4NTQ4ODY3NjY1OTI5QDE0MDA1MDcyOTAwMzA%3D&el=1_x_4&_esc=publicationCoverPdfhttps://www.researchgate.net/profile/Cathy-Streutker?enrichId=rgreq-886865cd06a9010c1cbe6e0c52aeb4d9-XXX&enrichSource=Y292ZXJQYWdlOzUxMjEyOTkyO0FTOjk4NTQ4ODY3NjY1OTI5QDE0MDA1MDcyOTAwMzA%3D&el=1_x_5&_esc=publicationCoverPdfhttps://www.researchgate.net/institution/University-of-Toronto?enrichId=rgreq-886865cd06a9010c1cbe6e0c52aeb4d9-XXX&enrichSource=Y292ZXJQYWdlOzUxMjEyOTkyO0FTOjk4NTQ4ODY3NjY1OTI5QDE0MDA1MDcyOTAwMzA%3D&el=1_x_6&_esc=publicationCoverPdfhttps://www.researchgate.net/profile/Cathy-Streutker?enrichId=rgreq-886865cd06a9010c1cbe6e0c52aeb4d9-XXX&enrichSource=Y292ZXJQYWdlOzUxMjEyOTkyO0FTOjk4NTQ4ODY3NjY1OTI5QDE0MDA1MDcyOTAwMzA%3D&el=1_x_7&_esc=publicationCoverPdfhttps://www.researchgate.net/profile/Lionel-Le-Bourhis?enrichId=rgreq-886865cd06a9010c1cbe6e0c52aeb4d9-XXX&enrichSource=Y292ZXJQYWdlOzUxMjEyOTkyO0FTOjk4NTQ4ODY3NjY1OTI5QDE0MDA1MDcyOTAwMzA%3D&el=1_x_4&_esc=publicationCoverPdfhttps://www.researchgate.net/profile/Lionel-Le-Bourhis?enrichId=rgreq-886865cd06a9010c1cbe6e0c52aeb4d9-XXX&enrichSource=Y292ZXJQYWdlOzUxMjEyOTkyO0FTOjk4NTQ4ODY3NjY1OTI5QDE0MDA1MDcyOTAwMzA%3D&el=1_x_5&_esc=publicationCoverPdfhttps://www.researchgate.net/institution/French-Institute-of-Health-and-Medical-Research?enrichId=rgreq-886865cd06a9010c1cbe6e0c52aeb4d9-XXX&enrichSource=Y292ZXJQYWdlOzUxMjEyOTkyO0FTOjk4NTQ4ODY3NjY1OTI5QDE0MDA1MDcyOTAwMzA%3D&el=1_x_6&_esc=publicationCoverPdfhttps://www.researchgate.net/profile/Lionel-Le-Bourhis?enrichId=rgreq-886865cd06a9010c1cbe6e0c52aeb4d9-XXX&enrichSource=Y292ZXJQYWdlOzUxMjEyOTkyO0FTOjk4NTQ4ODY3NjY1OTI5QDE0MDA1MDcyOTAwMzA%3D&el=1_x_7&_esc=publicationCoverPdfhttps://www.researchgate.net/profile/Susan-Robertson-3?enrichId=rgreq-886865cd06a9010c1cbe6e0c52aeb4d9-XXX&enrichSource=Y292ZXJQYWdlOzUxMjEyOTkyO0FTOjk4NTQ4ODY3NjY1OTI5QDE0MDA1MDcyOTAwMzA%3D&el=1_x_10&_esc=publicationCoverPdf

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nature medicine advance online publication �

TH17 cells are a subset of differentiated CD4+ T helper cells char-

acterized by secretion of IL-17 and IL-22. IL-17 is a cytokine with pleiotropic functions, including the recruitment and activation of neutrophils and activation of innate epithelial defense mecha-nisms1,2, whereas IL-22 acts as a mediator of mucosal barrier func-tion that elicits production of antimicrobial peptides and tissue repair factors by epithelial cells2,3. In cell culture systems, naive CD4+ T cells develop into TH17 cells through the combined action of the cytokines transforming growth factor-β and IL-6 (refs. 4,5), whereas sustained activation of these cells requires stimulation with IL-23 (ref. 6). In addition to TH17 cells, a variety of intestinal cells can secrete both IL-17 and IL-22, including CD8+ T cells, γδT cells, RAR-related orphan receptor γ–expressing natural killer and lymphoid tissue inducer (LTi) cells7–12.

The TH17 response is a crucial component of mucosal immunity to bacterial pathogens in the lung and intestine. In particular, the IL-17 and IL-22 axis mediates protection in a number of models of lung infection, including Klebsiella pneumoniae, Pseudomonas aeruginosa, Shigella flexneri and several Mycobacterium species13–18. In the gastrointestinal tract, IL-17 and IL-22 confer protection against Helicobacter pylori, Citrobacter rodentium and Salmonella enterica serovar Typhimurium19–23. C. rodentium–induced colitis triggers a robust colonic TH17 response by the second week after infection, which is required for full protection against this pathogen24,25. Streptomycin-pretreated mice infected with S. typhimurium develop an acute inflammatory response in the cecum, with IL-17 produced early (24–48 h) by γδT cells and other unidentified cells21,23,26.

Depending on the infection model used, IL-17 production in the intestine could occur immediately after infection (hours to days after infection)23,25 or at late stages (weeks after infection)24,25, sug-gesting the involvement of distinct levels of control by the innate and adaptive immune systems. In particular, early IL-17 production following bacterial infection suggest the existence of regulatory path-ways directly linking innate microbial detection to the activation of IL-17–producing cells. However, neither the host sensing systems responsible for inducing early IL-17 secretion nor the identity of the IL-17–producing cells providing early responses to bacterial patho-gens in vivo have been clearly identified.

Here we determined that the innate immune receptors Nod1 and Nod2 were crucial for induction of mucosal TH17 responses at early stages of infection in the cecum during C. rodentium- (4 d after infec-tion) and S. typhimurium-induced colitis (24 h after infection). We termed these cells innate TH17 cells (iTH17 cells) because of their early induction and their distinct regulation by Nod1 and Nod2 com-pared to late-stage (10 d after infection) adaptive-phase TH17 cells. Regulation of the intestinal Nod-iTH17 axis was dependent upon the expression of IL-6 and required intestinal microbiota for induction. Taken together, these results identify the Nod-iTH17 axis as a key element of mucosal immunity against bacterial pathogens.

RESULTSNod1 and Nod2 are required to control C. rodentium infectionNod1 and Nod2 are intracellular sensors of bacterial peptidoglycan, have key roles in host responses to bacteria27 and are implicated

1Department of Immunology, University of Toronto, Toronto, Ontario, Canada. 2Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada. 3Department of Laboratory Medicine, St. Michael’s Hospital, Toronto, Ontario, Canada. 4Department of Medicine, University of Toronto, Toronto, Ontario, Canada. 5These authors contributed equally to this work. Correspondence should be addressed to D.J.P. ([email protected]) or S.E.G. ([email protected]).

Received 23 February; accepted 2 May; published online 12 June 2011; doi:10.1038/nm.2391

Identification of an innate T helper type 17 response to intestinal bacterial pathogensKaoru Geddes1,5, Stephen J Rubino2,5, Joao G Magalhaes1, Catherine Streutker3, Lionel Le Bourhis1, Joon Ho Cho1, Susan J Robertson1, Connie J Kim4, Rupert Kaul1,4, Dana J Philpott1 & Stephen E Girardin2

Interleukin 17 (IL-17) is a central cytokine implicated in inflammation and antimicrobial defense. After infection, both innate and adaptive IL-17 responses have been reported, but the type of cells involved in innate IL-17 induction, as well as their contribution to in vivo responses, are poorly understood. Here we found that Citrobacter and Salmonella infection triggered early IL-17 production, which was crucial for host defense and was mediated by CD4+ T helper cells. Enteric innate T helper type 17 (iTH17) responses occurred principally in the cecum, were dependent on the Nod-like receptors Nod1 and Nod2, required IL-6 induction and were associated with a decrease in mucosal CD103+ dendritic cells. Moreover, imprinting by the intestinal microbiota was fully required for the generation of iTH17 responses. Together, these results identify the Nod-iTH17 axis as a central element in controlling enteric pathogens, which may implicate Nod-driven iTH17 responses in the development of inflammatory bowel diseases.

http://www.nature.com/doifinder/10.1038/nm.2391http://www.nature.com/naturemedicine/

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� advance online publication nature medicine

in cellular defense against C. rodentium infection in vitro28. To assess the in vivo importance of Nod1 and Nod2 in regulating mucosal inflammation, we used the C. rodentium–induced colitis

model. Infected Nod1−/− or Nod2−/− mice had no significant change in pathology or bacterial load when compared to wild-type mice (Supplementary Fig. 1a,b). However, we found that Nod1−/−Nod2−/−

mice had significantly lower pathological scores with less visible colonic inflamma-tion at 7 d after infection, as well as reduced inflammation-induced crypt elongation (Fig. 1a,b), although we observed no differ-ences in colonic colonization between the groups (Supplementary Fig. 1c). This ini-tially blunted colonic pathology observed in Nod1−/−Nod2−/− mice was followed by

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Figure 1 Nod1 and Nod2 differentially modulate early and late inflammation during C. rodentium-induced colitis. (a) The degree of colonic histopathology, crypt lengths and bacterial translocation to the spleen assessed in wild-type and Nod1−/−Nod2−/− mice at 7 and 14 d after infection. CFU, colony-forming units. (b) Representative images (20× magnification) of H&E-stained colon sections of wild-type and Nod1−/−Nod2−/− C. rodentium–infected mice at 7 and 14 d after infection; arrows depict areas of goblet cell depletion and submucosal edema; asterisks depict proximal regions of colon. (c) Degree of colonic histopathology, crypt length and splenic translocation in lethally irradiated wild-type mice reconstituted with either wild-type (WT→WT) or Nod1−/−Nod2−/− bone marrow (DKO→WT) and Nod1−/−Nod2−/− mice reconstituted with either wild-type (WT→DKO) or Nod1−/−Nod2−/− (DKO→DKO) bone marrow at 12 d after infection. Error bars represent s.e.m. *P < 0.05, **P < 0.01, ***P < 0.001. NS, not significant.

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Figure 2 Early IL-17 responses during C. rodentium–induced colitis are Nod1 and Nod2 dependent. (a) Il17a expression in C. rodentium–infected wild-type and Nod1−/−Nod2−/− mice, as quantified by quantitative RT-PCR (qRT-PCR) from the cecum at 4 d (top) and colon at 10 d (bottom) after infection. (b) Flow cytometry analysis of IL-17A and IL-22 intracellular cytokine staining (ICCS) of cecal LPLs from wild-type and Nod1−/−Nod2−/− mice (uninfected or 4 d), either of all LPLs (left) or CD4+TCRβ+ LPLs (right). (c) The relative number of CD4+TCRβ+IL-17A+ (TH17) cecal LPLs from wild-type and Nod1−/−Nod2−/− mice (uninfected or 4 d after C. rodentium infection, average of five replicates with three mice pooled per group). (d) Il22, Lcn2 and Reg3g expression in C. rodentium–infected wild-type and Nod1−/−Nod2−/− mice, as quantified by qRT-PCR in the cecum at 4 d after infection. For qRT-PCR, the average fold change in expression over PBS-treated wild-type mice is shown (n = 10, one representative of two experiments shown). Error bars represent s.e.m. *P < 0.05.

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exacerbated crypt hyperplasia and tenfold increased translocation of C. rodentium to the spleen (as measured by colony- forming units (CFU)) at 14 d after infection compared to what was observed in wild-type mice (Fig. 1a), indicating that Nod1−/− Nod2−/− mice could not effectively control the infection. Moreover, C. rodentium–induced inflammation frequently extended into the proximal colon of Nod1−/−Nod2−/− mice, whereas wild-type mice were affected only in the medial-distal region (Fig. 1b). Finally, whereas wild-type and Nod1−/−Nod2−/− mice did not succumb to infection with 1 × 109 CFU of C. rodentium, when we pretreated mice with naladixic acid and infected them with 1 × 1010 CFU of C. rodentium, Nod1−/−Nod2−/− mice were more susceptible and lost more weight than wild-type mice (Supplementary Fig. 1d).

We generated bone marrow chimeras by reconstituting wild-type mice with Nod1−/−Nod2−/− bone marrow (Nod1−/−Nod2−/−→wild-type), Nod1−/−Nod2−/− mice with wild-type bone marrow (wild-type→Nod1−/−Nod2−/−) and Nod1−/−Nod2−/− mice with Nod1−/−Nod2−/− bone marrow (Nod1−/−Nod2−/−→Nod1−/−Nod2−/−). All chimeric mice had increased splenic CFUs and pathology 12 d after C. rodentium infection compared to wild-type→wild-type mice (Fig. 1c), showing that Nod-dependent signaling in both radio-resistant and radio-sensitive compartments is required for the full control of the infection. Nevertheless, Nod-dependent signaling in the radio-resistant compartment had a more prominent role in the control of C. rodentium infection,

as Nod1−/−Nod2−/−-recipient mice, regardless of the origin of the donor bone marrow, had more bacterial translocation (Fig. 1c) and frequently developed ulcerations that we rarely observed in wild-type recipients (Supplementary Fig. 2a,b).

Nod1 and Nod2 are required to induce early TH17 responsesC. rodentium–induced colitis triggers a strong enteric TH17 response that modulates inflammation and bacterial colonization22; therefore we investigated the role of Nod1 and Nod2 in TH17 development in this infection model. At the peak of infection (10 d after infection), we detected similar Il17a expression in the colons of Nod1−/−Nod2−/− and wild-type mice, indicating that Nod proteins do not modulate the adaptive phase of TH17 responses to C. rodentium (Fig. 2a). However, Il17a expression was significantly reduced in cecal tissue from Nod1−/−Nod2−/− mice during the very early stages of infection (4 d after infection) (Fig. 2a). We observed significantly fewer IL-17A+CD4+ T cell receptor β (TCRβ)+ cecal lamina propria lymphocytes (LPLs) from Nod1−/−Nod2−/− mice than in wild-type LPLs at 4 d after infec-tion (Fig. 2b,c), but not at 10 d after infection, when roughly 30% of

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Figure 3 Acute IL-17 responses during S. typhimurium-induced colitis are dependent on hematopoietic and non-hematopoietic Nod1 and Nod2. (a) qRT-PCR analysis of Il17a, Il22 and Lcn2 in the cecum of wild-type and Nod1−/−Nod2−/− mice (uninfected or SL1344 infected for 24 h). Bar graphs show average fold change over uninfected controls (n = 6, one representative of three experiments shown). (b) ICCS analysis of IL-17A and IL-22 in total LPLs (top), CD4+TCRβ+ cells (middle) or TCRγδ+ cells (bottom) in cecal LPLs from wild-type and Nod1−/−Nod2−/− mice (uninfected or 24 h after infection with SL1344). (c) The average relative frequency of all cells, CD4+TCRβ+ IL-17A+ or TCRγδ+IL-17A+ cells in wild-type and Nod1−/−Nod2−/− mice (uninfected or 24 h after infection with SL1344, average of six replicates with three mice pooled per group). (d) qRT-PCR analysis for Il17a and Il22 on total cells (presort), CD4+ cells, CD11b+CD11c+ cells, and cells remaining after MACS purification (depleted). The bar graphs show fold change in expression over presort cells from uninfected mice (one representative of two replicates is shown, six mice pooled per group), and the numbers above the bars represent the fold change between wild-type and Nod1−/−Nod2−/− for each population of cells. (e) ICCS analysis of IL-17A and IL-22 in CD4+TCRβ+ cecal LPLs from chimeric mice (24 h after infection, one representative of three experiments is shown, three mice pooled per group). Error bars represent s.e.m. *P < 0.05, **P < 0.01.

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the colonic CD4+TCRβ+ LPLs were IL-17A+ in both wild-type and Nod1−/−Nod2−/− mice (Supplementary Fig. 3a). Of note, differ-ences in IL-17A+ cells were not evident in Nod1−/− or Nod2−/− mice (Supplementary Fig. 3b). At 4 d after infection, there were no sig-nificant differences in IL-17A expression in LPL γδT cells isolated from Nod1−/−Nod2−/− and wild-type mice (Supplementary Fig. 3c). We also determined that the number of interferon-γ–expressing CD4+TCRβ+ LPLs during the early phase of C. rodentium infection was similar between wild-type and Nod1−/−Nod2−/− mice, suggesting that Nod proteins can selectively induce TH17 and not TH1 responses during the early stages of intestinal inflammation (Supplementary Fig. 3c). In support of a blunted early TH17 response, the expression of the TH17-associated cytokine IL-22 in CD4

+ LPL T cells, as deter-mined by flow cytometric analysis or quantitative real-time PCR anal-ysis in cecal tissue, was also significantly reduced in Nod1−/−Nod2−/− mice at 4 d after infection compared to wild-type mice (Fig. 2b,d). Moreover, C. rodentium–infected Nod1−/−Nod2−/− cecal tissue had lower mRNA levels of Reg3g (encoding regenerating islet-derived 3γ) and Lcn2 (encoding lipocalin 2), antimicrobial proteins that are key mediators of IL-22–dependent mucosal defense against enteric bacterial pathogens (Fig. 2d)21,25,29.

To determine whether Nod1- and Nod2-dependent early induc-tion of TH17 responses was restricted to the C. rodentium model or a general host response to enteric infections, we assessed the role of Nod1 and Nod2 in an acute model of colitis induced by S. typhimurium in streptomycin-treated mice, for which we also have observed delayed intestinal pathology in Nod1−/−Nod2−/− mice30. By just 24 h after infection with SL1344 (a streptomycin-resistant strain of S. typhimurium), Nod1−/−Nod2−/− mice had significantly lower cecal expression of Il17a, Il22 and Lcn2 than wild-type mice

(Fig. 3a). Similarly to the C. rodentium model, there were fewer IL-17A+CD4+TCRβ+ LPLs recovered from Nod1−/−Nod2−/− mice compared to wild-type mice at this early stage of infection (Fig. 3b,c). However, in contrast to what was observed with C. rodentium, γδT cell–specific IL-17A expression in Nod1−/−Nod2−/− LPLs was blunted compared to wild-type LPLs after infection with SL1344 (Fig. 3b,c), probably reflecting a discrepancy between the models in terms of timing, with SL1344 inducing more severe and acute inflammation at an earlier time point.

To confirm that IL-17A and IL-22 were being produced primarily by CD4+ LPLs, we compared Il17a and Il22 expression in unsorted cells, CD4+ cecal lymphocytes and CD11b+CD11c+ dendritic cells (DCs) separated by magnetic-activated cell sort-ing (MACS) and cells remaining after CD4+ and CD11b+CD11c+ cell depletion. Indeed, the wild-type CD4+ cecal population expressed the highest levels of Il17a and Il22, and Nod1−/−Nod2−/− CD4+ cells expressed markedly less of these cytokines after infection (Fig. 3d).

In bone marrow–chimeric mice, we observed fewer IL-17A+ CD4+TCRβ+ LPLs in Nod1−/−Nod2−/−→Nod1−/−Nod2−/− mice com-pared to wild-type→wild-type mice during both SL1344 infection (Fig. 3e) and C. rodentium infection (Supplementary Fig. 3d,e). Nod1−/−Nod2−/−→wild-type and wild-type→Nod1−/−Nod2−/− chimeras infected with SL1344 showed intermediate levels of IL-17A+CD4+TCRβ+ cells in the LPL fraction (Fig. 3e), suggesting that Nod signaling from both hematopoietic and nonhematopoietic ources contributes to the early induction of mucosal IL-17A and IL-22 responses.

**

05

1015202530354045

0

1

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**

01,0002,0003,0004,0005,0006,0007,000

1.56

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Fol

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Presort CD4+ CD11b+

CD11c+Depleted

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Nod1

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Nod2

–/–

Nod1

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Nod2

–/–

Nod1

–/–

Nod2

–/–

Wild

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Nod1

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Nod2

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Nod2

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Nod2

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Il6 Il23r Il23aNS

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CD103

Figure 4 IL-6 expression during C. rodentium- and S. typhimurium (SL1344)-induced colitis are Nod1 and Nod2 dependent. (a) Expression of Il6, Il23r and Il23a in the cecum of wild-type and Nod1−/−Nod2−/− mice 4 d after infection with C. rodentium (top) or 24 h after infection with SL1344 (bottom). Average fold change over uninfected controls is shown (n = 6, one representative of three experiments is shown). (b) Cecal IL-6 amounts in SL1344-infected wild-type and Nod1−/−Nod2−/− mice (24, 48 and 72 h), as measured by ELISA. (c) Cecal IL-6 amounts in SL1344-infected chimeric mice, as measured by ELISA (n = 6, one representative of three experiments is shown). (d) qRT-PCR analysis for Il6 on total cells (presort), CD4+ cells, CD11b+CD11c+ cells and cells remaining after MACS purification (depleted). The bar graphs show fold change in expression over presort cells from uninfected mice (one representative of two replicates is shown, six mice pooled per group), and the numbers above the bars represent the fold change between wild type and Nod1−/−Nod2−/− for each population of cells. (e) Expression of CD103 on either CD11b− CD11c+ cells or CD11b+CD11c+ cecal IELs from wild-type (red) and Nod1−/−Nod2−/− (blue) mice uninfected, infected with C. rodentium for 4 d or infected with SL1344 for 24 h. One representative of three experiments, three mice pooled per group. Error bars represent s.e.m. *P < 0.05, **P < 0.01, ***P < 0.001.

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We also wanted to assess whether early TH17 responses can occur in the human intestinal mucosa. Isolated human intestinal lymphocytes showed a trend toward increased expression of IL-17A and IL-22 after an 8-h SL1344 challenge ex vivo (Supplementary Fig. 4).

IL-6 induction is required for early TH17 responsesTH17 development and activation are dependent on the inflamma-tory cytokines IL-6 and IL-23. Furthermore, the homeostatic TH17 response to enteric microbiota31 and the inflammatory TH17 response to C. rodentium22,25 both require functional IL-6 in vivo. Notably, we determined that in both C. rodentium–induced (Fig. 4a) and S. typhimurium–induced (Fig. 4a,b) colitis, early induction of Il6 in cecal tissue, but not of Il23a or the gene encoding its receptor, Il23r, was dependent on Nod1 and Nod2 signaling. Moreover, analysis of IL-6 expression in chimeras indicated that Nod1 and Nod2 signaling from both hematopoietic and nonhematopoietic cells regulates IL-6 production (Fig. 4c). Analysis of MACS-sorted cell populations indi-cated that Il6 mRNA was expressed in CD4+-sorted, CD11b+CD11c+-sorted and unsorted cecal cells (Fig. 4d), confirming the diverse cellular origins of this cytokine. However, only in the CD11b+CD11c+ DC fraction was there a substantial decrease in Il6 mRNA in infected Nod1−/−Nod2−/− mice compared to wild-type mice, indicating Nod1 and Nod2 are needed for full induction of Il6 in cecal DCs.

We further investigated how Nod1 and Nod2 signaling modulated CD11b+CD11c+ DC dynamics. The intestinal mucosa harbors distinct DC subsets that differentially express the surface marker CD103, corre-lating with either tolerogenic (CD103+) or pro-inflammatory (CD103−)

properties32,33. Hence, we assessed how Nod1 and Nod2 signaling in the intestinal mucosa affects the balance of CD103+ DCs during infection with SL1344 (24 h) and C. rodentium (4 d). In intraepithelial leukocytes (IELs), the numbers of CD103+CD11b+CD11c+ DCs were significantly reduced in wild-type but not Nod1−/−Nod2−/− mice after bacterial chal-lenge (Fig. 4e), which coincided with the

reduced inflammation and IL-17 responses of the Nod1−/−Nod2−/− mice after enteric infection.

Next, we investigated the requirement of IL-6 for the induction of early TH17 responses. At 24 h after infection with SL1344, wild-type mice treated with a neutralizing IL-6–specific antibody, but not with control IgG, failed to generate a robust TH17 response in cecal LPLs (Fig. 5a,b); γδT cells showed a trend toward decreased IL-17A production upon IL-6 neutralization, but these differences were not significant (Fig. 5b). In addition, we determined that only the TH17 response to SL1344, but not global induction of Il17a transcript levels or pathology (Supplementary Fig. 5), was blunted in Il6−/− mice (Fig. 5c). Furthermore, lack of IL-6 production by hematopoietic cells in Il6−/−→wild-type chimeric mice was sufficient to markedly decrease the numbers of TH17 cells at 24 h after SL1344 infection and 4 d after C. rodentium infection (Fig. 5d).

Induction of early TH17 requires intestinal microbiotaWe characterized the activation and memory state of the TH17 cells that are induced at early time points after bacterial infection. We determined that gated IL-17A+CD4+TCRβ+ LPLs showed a CD44+CD62L−CD69hiCCR6hi effector memory T cell pheno-type34 compared to IL-17A−CD4+T cells in the cecum (Fig. 6a). Homeostatic IL-17A+CD4+TCRβ+ LPLs were also CD44+CD62L−; however, SL1344 infection induced the upregulation of CD69 and CCR6 on these cells (Fig. 6a,b).

Intestinal bacteria, such as segmented filamentous bacteria (SFB), have been shown to influence the development of TH17 responses

35.

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Wild type Wild typeIl6–/– Il6–/– Wild type Il6–/–

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0.55

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0102

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a

c

d

b Figure 5 IL-6 expression during the acute phase of infectious colitis is crucial for TH17 development. (a) ICCS analysis of IL-17A and IL-22 on total cecal LPLs (top), CD4+TCRβ+ cells (middle) or TCRγδ+ cells (bottom) from SL1344-infected wild-type mice (uninfected or 24 h after infection) treated with either control IgG or IL-6–neutralizing antibody (anti–IL-6). (b,c) Average relative frequency of all IL-17A+, CD4+TCRβ+IL-17A+ or TCRγδ+IL-17A+ cells from control IgG– or IL-6–neutralizing antibody–treated, SL1344–infected or uninfected wild-type mice (b) and SL1344-infected or uninfected wild-type and IL-6–knockout mice (c) (24 h after infection, average of three replicates with three mice pooled per group). (d) ICCS analysis for IL-17A and IL-22 expression in TCRβ+CD4+ cecal LPLs from C. rodentium–infected (4 d) and SL1344-infected (24 h) chimeric mice that were generated by reconstituting irradiated wild-type mice with either wild-type (WT→WT) or Il6−/− (Il6−/−→WT) bone marrow. Dot plots depict one representative of three experiments with two mice pooled per group. Error bars represent s.e.m. *P < 0.05, **P < 0.01.

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Notably, our mouse colony harbors SFB, but we found, just as others have reported35, that Nod1 and Nod2 did not influence colonization by these bacteria and that SFB preferentially colonized the ileum and were virtually absent from the cecum (Supplementary Fig. 6).

We postulated that TH17 cells in the lamina propria might be conditioned by the intestinal microbiota to induce a state that can rapidly respond to subsequent bacterial infections. To address the importance of the microbiota in the generation of early TH17 responses, we compared the mucosal IL-17A responses in germ-free or specific pathogen–free (SPF) mice. We determined that, as previously reported36, uninfected germ-free mice had considerably fewer TH17 LPLs than SPF mice (Fig. 6c,d). However, the global numbers of IL-17A+LPLs were not significantly reduced, as there was a large increase in the number of IL-17A+γδT cells in germ-free mice (Fig. 6c,d). This observation indicated that mucosal IL-17A responses have some degree of plasticity in the cecum, where other cell types can compensate for the loss of IL-17A expression by TH17 cells. We also observed a similar compensation in IL-17A produc-tion after depletion of CD4+ cells (Supplementary Fig. 7). Of note, 24 h after SL1344 infection there were markedly fewer TH17 cells in germ-free mice compared to SPF mice (Fig. 6c,d). The numbers of IL-17A+CD4+TCRβ+ cells actually decreased substantially after infec-tion in germ-free cecal LPLs compared to uninfected mice (Fig. 6c,d).

DISCUSSIONElucidating the role of Nod proteins in intestinal barrier defense is essential for understanding the etiology of inflammatory bowel disease (IBD). In this study, we investigated the role of Nod1 and Nod2 in regulating TH17 responses during C. rodentium and S. typhimurium colitis. Nod1−/−Nod2−/− mice do not efficiently generate early TH17 responses in the cecum in both colitis mod-els. We therefore propose the term iTH17 for these cells owing to their dependency on Nod1 and Nod2 signaling for activation at

early time points after bacterial infection (1–4 d after infection). Notably, the lack of a protective iTH17 response correlates with delayed pathology and increased disease burden in Nod1−/−Nod2−/− mice infected with C. rodentium. These results represent what is to our knowledge the first identification of a role for innate immune sensors in the control of TH17 induction in the intestine, and they suggest that Nod proteins contribute to the regulation of the bal-ance between signals from the intestinal microbiota and from enteric pathogens. This illustrates the expanding functional com-plexity of intestinal TH17 responses in conditions of homeostasis or pathogenic infection.

The kinetics of mucosal iTH17 induction after C. rodentium and S. typhimurium infection are not compatible with the kinetics of a prototypic adaptive immune response. LTi-like cells are an innate source of IL-17A and IL-22 in Rag1−/− mice12,37. However, our study identifies lamina propria iTH17 cells as an innate source of IL-17A and IL-22 in wild-type mice using in vivo infection models. This unexpected observation suggests that TH17 cells may have innate-like properties. The iTH17 response does not seem to be a nonspecific activation of lamina propria TH17 cells, as iTH17 cells fail to develop in the absence of microbiota, even though TH17 cells were present in germ-free mice before infection. Although iTh17 express effec-tor memory cell–associated surface markers, it is not clear whether bacteria-specific antigens or other microbiota-derived products are required for priming the response. Further analysis is warranted to

a

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γδT cells

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01,0002,0003,0004,0005,0006,0007,0008,0009,000

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0102 103 104 105

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Figure 6 Early TH17 cells express memory surface markers and require microbiota for activation. (a) Expression of CD44, CD62L, CD69 and CCR6 on either all CD4+TCRβ+ cells or CD4+TCRβ+IL-17A+ cells in cecal LPLs from SL1344-infected mice (top) or expression of these cell surface markers on CD4+TCRβ+IL-17A+cells from the LPLs of uninfected and SL1344-infected mice (24 h after infection) (bottom). (b) Mean fluorescence intensity (MFI) of CD69 expression on LPLs from uninfected or SL1344-infected mice (average of three replicates with three mice pooled per group). (c) ICCS analysis of IL-17A and IL-22 in total cecal LPLs (top), CD4+TCRβ+ cells (middle) or TCRγδ+ cells (bottom) from SL1344-infected SPF and germ-free mice (uninfected or 24 h after infection). (d) Average relative frequency of all IL-17A+, CD4+TCRβ+ IL-17A+ or TCRγδ+IL-17A+ cells from SL1344-infected SPF and germ-free mice (uninfected or 24 h after infection) (uninfected group had two replicates, infected group had three replicates, three mice pooled per group). Error bars represent s.e.m. *P < 0.05, **P < 0.01.

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investigate the role of the microbiota in the development of iTH17 responses. Together, our results suggest that Nod-iTH17 responses represent a rapid, bacteria-specific protective response in the intes-tine that bridges the gap until adaptive TH1, TH2, or TH17 responses are fully developed.

In contrast to previous studies showing that IL-23 regulates IL-17 from innate sources such as LTi and γδT cells, we show that IL-6 is essential for the development of iTH17 responses. In our models, IL-6 is the only factor implicated in TH17 development whose expression is substantially influenced by Nod1 and Nod2. Furthermore, we show that Nod1 and Nod2 regulate Il6 expression in sorted DCs and that CD11c+CD11b+CD103+ DC populations are modulated in a Nod-dependent manner during infection. These data strongly suggest that Nod1 and Nod2 regulate iTH17 responses through modulation of IL-6 expression in DCs. Nod1 and Nod2 are involved in the develop-ment of adaptive TH17 responses in mouse

38 and human39 cells in an IL-23–dependent manner. Although we find that Il23a is expressed at high baseline levels its expression is not dependent on Nod1 and Nod2 and is not significantly induced at very early times of infection. Thus, the discrepancy in the requirement of IL-23 or IL-6 in these studies is likely to be due to the difference in kinetics and the differ-ent model systems involved. Of note, although IL-23 does not seem to be directly modulated by Nod1 and Nod2, we believe it probably works in concert with IL-6 to drive the iTH17 responses, as early IL-17 responses during both S. typhimurium and C. rodentium colitis are IL-23 dependent23,25.

A growing body of evidence suggests that defective homeostatic immune control of the intestinal microbiota, or impaired responses to microbial pathogens, might have roles in the development of intes-tinal inflammation. Notably, several studies in individuals with IBD have identified risk-associated single nucleotide polymorphisms in Nod-like receptor genes and in loci associated with TH17 responses, including IL23R, IL22 and STAT340, providing independent evidence that Nod-like receptors and pathways controlling IL-17 expression both play key parts in intestinal immune homeostasis. Thus, the intes-tinal Nod-iTH17 axis that we have identified in this report provides new mechanistic insights into the pathophysiology of the IBD condi-tions Crohn’s disease and ulcerative colitis.

METHODSMethods and any associated references are available in the online version of the paper at http://www.nature.com/naturemedicine/.

Note: Supplementary information is available on the Nature Medicine website.

ACKnowLEDGMEntSWe thank L. Morikawa for help with preparing histological sections and K. Banks for help with animal experimentation. We also are very grateful to those individuals who volunteered for intestinal biopsies. Nod2−/− mice were provided by J.P. Hugot at Institut National de la Santé et de la Recherche Médicale U843. C. rodentium strain DBS100 was provided by B. Finlay at the University of British Columbia. This work was supported by a grant from the Crohn’s and Colitis Foundation of Canada to S.E.G., a Crohn’s and Colitis Foundation of Canada and a Canadian Institute of Health Research operating grant (480142) to D.J.P. and by a Canadian Institutes of Health Research grant (HET-85518) and an Ontario HIV Treatment Network grant (OGB-G123) to R.K. K.G. was supported by a Canadian Association of Gastroenterology/Canadian Institutes of Health Research postdoctoral research award, and S.J.R. was supported by a Fonds de la Recherche en Santé du Québec graduate scholarship.

AUtHoR ContRIBUtIonSK.G. and S.J.R. designed and performed all experiments and wrote the manuscript. J.G.M. designed and performed mouse experiments. C.S. performed pathological scoring analysis. L.L.B. generated the Nod1−/−Nod2−/− mice. J.H.C. and S.J.R.

performed microbiota analysis. C.J.K. and R.K. provided human colonic samples. D.J.P. and S.E.G. directed the research and wrote the manuscript.

CoMPEtInG FInAnCIAL IntEREStSThe authors declare no competing financial interests.

Published online at http://www.nature.com/naturemedicine/. Reprints and permissions information is available online at http://www.nature.com/reprints/index.html.

1. Bettelli, E., Korn, T., Oukka, M. & Kuchroo, V.K. Induction and effector functions of TH17 cells. Nature 453, 1051–1057 (2008).

2. Ouyang, W., Kolls, J.K. & Zheng, Y. The biological functions of T helper 17 cell effector cytokines in inflammation. Immunity 28, 454–467 (2008).

3. Colonna, M. Interleukin-22–producing natural killer cells and lymphoid tissue inducer-like cells in mucosal immunity. Immunity 31, 15–23 (2009).

4. Bettelli, E. et al. Reciprocal developmental pathways for the generation of pathogenic effector TH17 and regulatory T cells. Nature 441, 235–238 (2006).

5. Veldhoen, M., Hocking, R.J., Atkins, C.J., Locksley, R.M. & Stockinger, B. TGFβ in the context of an inflammatory cytokine milieu supports de novo differentiation of IL-17–producing T cells. Immunity 24, 179–189 (2006).

6. Littman, D.R. & Rudensky, A.Y. TH17 and regulatory T cells in mediating and restraining inflammation. Cell 140, 845–858 (2010).

7. Takatori, H. et al. Lymphoid tissue inducer-like cells are an innate source of IL-17 and IL-22. J. Exp. Med. 206, 35–41 (2009).

8. Billerbeck, E. et al. Analysis of CD161 expression on human CD8+ T cells defines a distinct functional subset with tissue-homing properties. Proc. Natl. Acad. Sci. USA 107, 3006–3011 (2010).

9. Satoh-Takayama, N. et al. Microbial flora drives interleukin 22 production in intestinal NKp46+ cells that provide innate mucosal immune defense. Immunity 29, 958–970 (2008).

10. Cella, M. et al. A human natural killer cell subset provides an innate source of IL-22 for mucosal immunity. Nature 457, 722–725 (2009).

11. Martin, B., Hirota, K., Cua, D.J., Stockinger, B. & Veldhoen, M. Interleukin-17–producing γδ T cells selectively expand in response to pathogen products and environmental signals. Immunity 31, 321–330 (2009).

12. Sonnenberg, G.F., Monticelli, L.A., Elloso, M.M., Fouser, L.A. & Artis, D. CD4+ lymphoid tissue-inducer cells promote innate immunity in the gut. Immunity 34, 122–134 (2011).

13. Aujla, S.J. et al. IL-22 mediates mucosal host defense against Gram-negative bacterial pneumonia. Nat. Med. 14, 275–281 (2008).

14. Priebe, G.P. et al. IL-17 is a critical component of vaccine-induced protection against lung infection by lipopolysaccharide-heterologous strains of Pseudomonas aeruginosa. J. Immunol. 181, 4965–4975 (2008).

15. Khader, S.A. et al. IL-23 and IL-17 in the establishment of protective pulmonary CD4+ T cell responses after vaccination and during Mycobacterium tuberculosis challenge. Nat. Immunol. 8, 369–377 (2007).

16. Umemura, M. et al. IL-17–mediated regulation of innate and acquired immune response against pulmonary Mycobacterium bovis bacille Calmette-Guerin infection. J. Immunol. 178, 3786–3796 (2007).

17. Wu, Q. et al. IL-23–dependent IL-17 production is essential in neutrophil recruitment and activity in mouse lung defense against respiratory Mycoplasma pneumoniae infection. Microbes Infect. 9, 78–86 (2007).

18. Sellge, G. et al. TH17 cells are the dominant T cell subtype primed by Shigella flexneri mediating protective immunity. J. Immunol. 184, 2076–2085 (2010).

19. Velin, D. et al. Interleukin-17 is a critical mediator of vaccine-induced reduction of Helicobacter infection in the mouse model. Gastroenterology 136, 2237–2246 (2009).

20. Raffatellu, M. et al. Simian immunodeficiency virus–induced mucosal interleukin-17 deficiency promotes Salmonella dissemination from the gut. Nat. Med. 14, 421–428 (2008).

21. Raffatellu, M. et al. Lipocalin-2 resistance confers an advantage to Salmonella enterica serotype Typhimurium for growth and survival in the inflamed intestine. Cell Host Microbe 5, 476–486 (2009).

22. Ishigame, H. et al. Differential roles of interleukin-17A and -17F in host defense against mucoepithelial bacterial infection and allergic responses. Immunity 30, 108–119 (2009).

23. Godinez, I. et al. Interleukin-23 orchestrates mucosal responses to Salmonella enterica serotype Typhimurium in the intestine. Infect. Immun. 77, 387–398 (2009).

24. Symonds, E.L. et al. Involvement of T helper type 17 and regulatory T cell activity in Citrobacter rodentium invasion and inflammatory damage. Clin. Exp. Immunol. 157, 148–154 (2009).

25. Zheng, Y. et al. Interleukin-22 mediates early host defense against attaching and effacing bacterial pathogens. Nat. Med. 14, 282–289 (2008).

26. Godinez, I. et al. T cells help to amplify inflammatory responses induced by Salmonella enterica serotype Typhimurium in the intestinal mucosa. Infect. Immun. 76, 2008–2017 (2008).

27. Geddes, K., Magalhaes, J.G. & Girardin, S.E. Unleashing the therapeutic potential of NOD-like receptors. Nat. Rev. Drug Discov. 8, 465–479 (2009).

http://www.nature.com/naturemedicine/

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11 N

atu

re A

mer

ica,

Inc.

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erve

d.

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28. LeBlanc, P.M. et al. Caspase-12 modulates NOD signaling and regulates antimicrobial peptide production and mucosal immunity. Cell Host Microbe 3, 146–157 (2008).

29. Cash, H.L., Whitham, C.V., Behrendt, C.L. & Hooper, L.V. Symbiotic bacteria direct expression of an intestinal bactericidal lectin. Science 313, 1126–1130 (2006).

30. Geddes, K. et al. Nod1 and Nod2 regulation of inflammation in the Salmonella colitis model. Infect. Immun. 78, 5107–5115 (2010).

31. Ivanov, I.I. et al. The orphan nuclear receptor RORgammat directs the differentiation program of proinflammatory IL-17+ T helper cells. Cell 126, 1121–1133 (2006).

32. Coombes, J.L. & Powrie, F. Dendritic cells in intestinal immune regulation. Nat. Rev. Immunol. 8, 435–446 (2008).

33. Niess, J.H. & Adler, G. Enteric flora expands gut lamina propria CX3CR1+ dendritic cells supporting inflammatory immune responses under normal and inflammatory conditions. J. Immunol. 184, 2026–2037 (2010).

34. Dutton, R.W., Bradley, L.M. & Swain, S.L. T cell memory. Annu. Rev. Immunol. 16, 201–223 (1998).

35. Ivanov, I.I. et al. Induction of intestinal TH17 cells by segmented filamentous bacteria. Cell 139, 485–498 (2009).

36. Ivanov, I.I. et al. Specific microbiota direct the differentiation of IL-17–producing T-helper cells in the mucosa of the small intestine. Cell Host Microbe 4, 337–349 (2008).

37. Buonocore, S. et al. Innate lymphoid cells drive interleukin-23–dependent innate intestinal pathology. Nature 464, 1371–1375 (2010).

38. Fritz, J.H. et al. Nod1-mediated innate immune recognition of peptidoglycan contributes to the onset of adaptive immunity. Immunity 26, 445–459 (2007).

39. van Beelen, A.J. et al. Stimulation of the intracellular bacterial sensor NOD2 programs dendritic cells to promote interleukin-17 production in human memory T cells. Immunity 27, 660–669 (2007).

40. Cho, J.H. The genetics and immunopathogenesis of inflammatory bowel disease. Nat. Rev. Immunol. 8, 458–466 (2008).

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11 N

atu

re A

mer

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Inc.

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rig

hts

res

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d.

nature medicinedoi:10.1038/nm.2391

ONLINE METHODSMice. C57BL/6 (Charles River), Il6−/− (Jackson Laboratories), germ-free and SPF Swiss-Webster (Taconic Farms), Nod1−/− (Millenium Pharmaceuticals), Nod2−/− and Nod1−/−Nod2−/− mice (see Supplementary Methods for details) were bred and housed under SPF conditions at the Center for Cellular and Biomolecular Research, University of Toronto (see details in Supplementary Methods). No gender-specific differences were observed in the colitis models; therefore both male and female mice were used, but within experiments gender and age were matched. All mouse experiments were approved by the Animal Ethics Review Committee of the University of Toronto.

Bacterial infections. Unless otherwise indicated, 1 × 109 CFU of an overnight culture of naladixic acid–resistant C. rodentium strain DBS100 were used to infect 6- to 10-week-old mice that were fasted for 3 h. For S. typhimurium infec-tions, mice were fasted for 3 h and then orally administered 20 mg of strep-tomycin; 24 h later the mice were fasted again before oral inoculation with 5 × 107 CFU of an overnight culture of SL1344, a streptomycin-resistant strain of S. typhimurium41. C. rodentium colonic and splenic colonization was determined by homogenizing fecal pellets or spleens in PBS using a rotor homogenizer fol-lowed by serial dilution plating on naladixic acid–containing LB plates.

Pathological scoring. Mouse colons were collected and cleaned, cut open longi-tudinally and rolled, and then fixed with 10% (vol/vol) formalin. Fixed samples were stained with H&E at the Toronto Center of Phenogenomics by standard procedures. Pathological scoring was performed by a pathologist specializ-ing in intestinal inflammation using a previously established system to assess C. rodentium pathology42.

Chimeras. Chimeras were generated by irradiating recipient mice with 900 cGy of ionizing radiation. One day later, these mice were reconstituted with 4 × 106 donor mouse bone marrow cells. The mice were then allowed to reconstitute for at least 6 weeks before experimental procedures.

Quantitative real-time PCR. Cecum and colon samples for qRT-PCR were col-lected and stored in RNAlater (Sigma), then RNA was extracted with Qiagen RNeasy Extraction kits. Genomic DNA was digested with Turbo DNase (Ambion) before reverse transcription to cDNA with SuperScript RTIII (Invitrogen). qRT-PCR was performed with either SYBR Green (Applied Biosystems) or TaqMan probes (ABI) (see Supplementary Methods for primer details). Values were calculated using the ∆Ct method and were normalized to the housekeeping gene Rpl19.

Enzyme-linked immunosorbent assay. Ceca were excised, washed and then placed in ice-cold PBS. Tissue was weighed and homogenized with a rotor homogenizer, and then samples were centrifuged and supernatants were col-lected. IL-6 amounts in the supernatants were quantified by ELISA (R&D Systems) and normalized to tissue weight.

In vivo cytokine neutralization. For in vivo cytokine neutralization, IL-6 neu-tralizing antibody (R&D systems, AB-406-NA), or control IgG (AB-108-C) was intraperitoneally injected at 48, 24, 4 and 0 h (50 µg per injection) before SL1344 infection and again at 4 h after infection (75 µg).

Lamina propria lymphocyte and intraepithelial leukocyte isolation. Cecal tissue was extracted, washed and cut into 1- to 2-cm segments that were incubated three times (37 °C, 10 min) in stripping buffer (PBS, 1% FBS, 5 mM EDTA, 1 mM DTT). After each incubation, the buffer was filtered through a 100-µm cell strainer and then allowed to sediment. IELs were collected by centrifuging the cells that did not sediment, washing twice in DMEM (20% FBS) and passing through a 40-µm cell strainer. After stripping, the tissue segments were minced and digested in digestion buffer (DMEM, 20% FBS, 2 mg ml−1 collagenase D (Roche), 20 µg ml−1 DNaseI (Sigma)) for two 30-min incubations at 37 °C. Digested material was passed through a 100-µm cell strainer, and the cells were collected by centrifugation, washed twice in DMEM and then passed through a 40-µm cell strainer to obtain LPLs.

Flow cytometry. For ICCS, LPLs and IELs were incubated for 4 h with DMEM containing phorbol-12-myristate-13-acetate (50 ng ml−1), ionomycin (Sigma) (1 µg ml−1) and Golgi Stop (BD bioscience). Dead cells were stained with violet live/dead fixable stain (Invitrogen), and then LPLs and IELs were stained for surface antigens (see Supplementary Methods for antibody list). Cells were then fixed with 4% paraformaldehyde (wt/vol) and permeabilized with BD Perm/Wash buffer (BD Bioscience) and stained for intracellular cytokines. FACS analysis was performed with either a Canto II or LSR II (BD bioscience) flow cytometer and analyzed with FlowJo software (TreeStar).

Cell sorting. Magnetic bead–conjugated antibodies to CD4, CD11c and CD11b were used to label cecal IELs and LPLcells, and these cells were then sorted with LS columns (Miltenyi Biotec) according to the manufacturer’s protocol (see Supplementary Methods for flow-cytometry control staining of sorted popula-tions). RNA was immediately isolated from sorted cells as described above.

Statistical analyses. Mann-Whitney tests or Student’s t tests were performed using Graphpad (Prism), and P values < 0.05 using a 95% confidence interval were considered significant.

Additional methods. Detailed methodology is described in the Supplementary Methods.

41. Barthel, M. et al. Pretreatment of mice with streptomycin provides a Salmonella enterica serovar Typhimurium colitis model that allows analysis of both pathogen and host. Infect. Immun. 71, 2839–2858 (2003).

42. Gibson, D.L. et al. MyD88 signalling plays a critical role in host defence by controlling pathogen burden and promoting epithelial cell homeostasis during Citrobacter rodentium–induced colitis. Cell. Microbiol. 10, 618–631 (2008).

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https://www.researchgate.net/publication/51212992

Identification of an innate T helper type 17 response to intestinal bacterial pathogensRESULTSNod1 and Nod2 are required to control C. rodentium infectionNod1 and Nod2 are required to induce early TH17 responsesIL-6 induction is required for early TH17 responsesInduction of early TH17 requires intestinal microbiota

DISCUSSIONMethodsONLINE METHODSMice.Bacterial infections.Pathological scoring.Chimeras.Quantitative real-time PCR.Enzyme-linked immunosorbent assay.In vivo cytokine neutralization.Lamina propria lymphocyte and intraepithelial leukocyte isolation.Flow cytometry.Cell sorting.Statistical analyses.Additional methods.

AcknowledgmentsAUTHOR CONTRIBUTIONSCOMPETING FINANCIAL INTERESTSReferences

Figure 1 Nod1 and Nod2 differentially modulate early and late inflammation during C. rodentium-Figure 2 Early IL-17 responses during Figure 3 Acute IL-17 responses during Figure 4 IL-6 expression during C. rodentium- Figure 5 IL-6 expression during the acute Figure 6 Early TH17 cells express memory

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