title: Interleukin-17 as a molecular target in immune-mediated arthritis: immunoregulatory properties of genetically modified murine dendritic cells that secrete interleukin-4.
abstract: OBJECTIVE
  Our previous studies have shown that murine dendritic cells (DCs) genetically modified to express interleukin-4 (IL-4) reduce the incidence and severity of murine collagen-induced arthritis. The present studies were performed to assess the immunoregulatory mechanisms underlying this response, by assessing the effects of IL-4 DCs on cytokine production by subsets of T helper cells.
  
  
  METHODS
  Male DBA mice ages 6-8 weeks old were immunized with type II collagen. Splenic T cells obtained during the initiation phase and the end stage of arthritis were cultured with IL-4 DCs or untransduced DCs in the presence of collagen rechallenge. Interferon-gamma (IFNgamma) and IL-17 responses were measured. Antibodies to IL-4, IL-12, and IL-23, and recombinant IL-4, IL-12, and IL-23 were used to further study the regulation of T cell cytokine production by IL-4 DCs.
  
  
  RESULTS
  Splenic T cells obtained during the initiation phase of arthritis produced less IL-17 when cultured in the presence of IL-4 DCs, despite their production of increased quantities of other proinflammatory cytokines (IFNgamma and tumor necrosis factor). T cell IL-17 production after collagen rechallenge was not inhibited by a lack of IL-23, since IL-4-mediated suppression of IL-17 was not reconstituted by IL-23, an otherwise potent inducer of IL-17 production by T cells. Although IL-4 DCs can produce increased quantities of IL-12 and IFNgamma, suppression of IL-17 production by IL-4 DCs was independent of both. While IL-17 production by T cells obtained during the initiation phase of arthritis was regulated by IL-4 DCs, IL-17 production by T cells obtained during end-stage arthritis was not altered.
  
  
  CONCLUSIONS
  Our data suggest that IL-4 DCs exert a therapeutic effect on collagen-induced arthritis by targeting IL-17. IL-17 suppression by IL-4 DCs is robust and is not reversed by IL-23. Timing might be important in IL-17-targeted therapy, since IL-17 production by T cells obtained during end-stage arthritis did not respond to suppression by IL-4 DCs.
authors.affiliation: University of Michigan, Ann Arbor, MI 48109, USA.
authors.forename: Sujata
authors.initials: S
authors.lastname: Sarkar
authors.forename: Laura A
authors.initials: LA
authors.lastname: Tesmer
authors.forename: Vindhya
authors.initials: V
authors.lastname: Hindnavis
authors.forename: Judith L
authors.initials: JL
authors.lastname: Endres
authors.forename: David A
authors.initials: DA
authors.lastname: Fox
mesh_terms: D000818:Animals; D019138:Antibodies, Blocking / Q000494:pharmacology; D001169:Arthritis, Experimental / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D001172:Arthritis, Rheumatoid / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D023201:CD40 Ligand / Q000494:pharmacology; D002478:Cells, Cultured; D003713:Dendritic Cells / Q000187:drug effects / Q000378:metabolism*; D007108:Immune Tolerance; D007371:Interferon-gamma / Q000378:metabolism; D020381:Interleukin-17 / Q000276:immunology / Q000378:metabolism*; D015847:Interleukin-4 / Q000276:immunology / Q000378:metabolism*; D008297:Male; D051379:Mice; D008811:Mice, Inbred DBA; D013154:Spleen / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology / Q000378:metabolism
chemical_list: D019138:Antibodies, Blocking; D020381:Interleukin-17; D023201:CD40 Ligand; D015847:Interleukin-4; D007371:Interferon-gamma