title: Card9 mediates intestinal epithelial cell restitution, T-helper 17 responses, and control of bacterial infection in mice.
abstract: OBJECTIVE
  Caspase recruitment domain 9 (CARD9) is an adaptor protein that integrates signals downstream of pattern recognition receptors. CARD9 has been associated with autoinflammatory disorders, and loss-of-function mutations have been associated with chronic mucocutaneous candidiasis, but the role of CARD9 in intestinal inflammation is unknown. We characterized the role of Card9 in mucosal immune responses to intestinal epithelial injury and infection.
  
  
  METHODS
  We induced intestinal inflammation in Card9-null mice by administration of dextran sulfate sodium (DSS) or Citrobacter rodentium. We analyzed body weight, assessed inflammation by histology, and measured levels of cytokines and chemokines using quantitative reverse-transcription polymerase chain reaction and enzyme-linked immunosorbent assay. Cell populations were compared between wild-type and Card9-null mice by flow cytometry analysis.
  
  
  RESULTS
  Colon tissues and mesenteric lymph nodes of Card9-null mice had reduced levels of interleukin (IL)-6, interferon-γ, and T-helper (Th)17 cytokines after administration of DSS, compared with wild-type mice. IL-17A and IL-22 expression were reduced in the recovery phase after DSS administration, coincident with decreased expression of antimicrobial peptides and the chemokine (C-C motif) ligand 20 (Ccl20). Although Card9-null mice had more intestinal fungi based on 18S analysis, their Th17 responses remained defective even when an antifungal agent was administered throughout DSS exposure. Moreover, Card9-null mice had impaired immune responses to C rodentium, characterized by decreased levels of colonic IL-6, IL-17A, IL-22, and regenerating islet-derived 3 gamma (RegIIIγ), as well as fewer IL-22-producing innate lymphoid cells (ILCs) in colon lamina propria.
  
  
  CONCLUSIONS
  The adaptor protein CARD9 coordinates Th17- and innate lymphoid cell-mediated intestinal immune responses after epithelial injury in mice.
authors.affiliation: Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
authors.forename: Harry
authors.initials: H
authors.lastname: Sokol
authors.forename: Kara L
authors.initials: KL
authors.lastname: Conway
authors.forename: Mei
authors.initials: M
authors.lastname: Zhang
authors.forename: Myunghwan
authors.initials: M
authors.lastname: Choi
authors.forename: Bret
authors.initials: B
authors.lastname: Morin
authors.forename: Zhifang
authors.initials: Z
authors.lastname: Cao
authors.forename: Eduardo J
authors.initials: EJ
authors.lastname: Villablanca
authors.forename: Chun
authors.initials: C
authors.lastname: Li
authors.forename: Cisca
authors.initials: C
authors.lastname: Wijmenga
authors.forename: Seok Hyun
authors.initials: SH
authors.lastname: Yun
authors.forename: Hai Ning
authors.initials: HN
authors.lastname: Shi
authors.forename: Ramnik J
authors.initials: RJ
authors.lastname: Xavier
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism*; D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D053468:CARD Signaling Adaptor Proteins; D044082:Citrobacter rodentium; D003092:Colitis / Q000209:etiology / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D016207:Cytokines / Q000378:metabolism; D016264:Dextran Sulfate; D004756:Enterobacteriaceae Infections / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005434:Flow Cytometry; D007113:Immunity, Innate; D007413:Intestinal Mucosa / Q000276:immunology / Q000378:metabolism* / Q000382:microbiology / Q000473:pathology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D020133:Reverse Transcriptase Polymerase Chain Reaction; D058504:Th17 Cells / Q000378:metabolism*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D015415:Biomarkers; D053468:CARD Signaling Adaptor Proteins; C513280:Card9 protein, mouse; D016207:Cytokines; D016264:Dextran Sulfate
keywords: AMP; ASCA; CARD9; CFU; Ccl20; Colitis; DSS; IFN; IL; ILC; Inflammatory Response; JNK; LP; MLN; Mouse Model; PBS; SFB; T-helper; TNF; Th; antimicrobial peptide; anti–Saccharomyces cerevisiae antibody; c-Jun-N-terminal kinase; caspase recruitment domain 9; chemokine (C-C motif) ligand 20; colony forming unit; dextran sulfate sodium; innate lymphoid cell; interferon; interleukin; lamina propria; mesenteric lymph node; phosphate-buffered saline; qRT-PCR; quantitative reverse-transcription polymerase chain reaction; segmented filamentous bacteria; tumor necrosis factor