title: Different amplifying mechanisms of interleukin-17 and interferon-gamma in Fcgamma receptor-mediated cartilage destruction in murine immune complex-mediated arthritis.
abstract: OBJECTIVE
  Previously, we reported that interferon-gamma (IFNgamma) aggravates cartilage destruction in immune complex (IC)-mediated arthritis via up-regulation of activating Fcgamma receptors (FcgammaR). Recently, we found that interleukin-17 (IL-17) also aggravates cartilage destruction in arthritis models in which ICs are involved, but the underlying mechanism remains unknown. This study was undertaken to determine the role of IL-17 in FcgammaR-mediated cartilage destruction in IC-mediated arthritis and to compare its effect with that of IFNgamma.
  
  
  METHODS
  IC-mediated arthritis was passively induced in gamma-chain(-/-) mice, which lack functional activating FcgammaR, and in wild-type controls. AdIL-17 or a control vector was injected into the knee joints 1 day prior to induction of IC-mediated arthritis. Knee joints were isolated for histologic analysis, and synovium samples were obtained for reverse transcriptase-polymerase chain reaction (RT-PCR). Macrophage (RAW 264.7) cell lines and polymorphonuclear cell (PMN; 32Dcl3) lines were stimulated with IFNgamma or IL-17 for analysis of FcgammaR expression using RT-PCR and fluorescence-activated cell sorting.
  
  
  RESULTS
  IL-17 overexpression prior to induction of IC-mediated arthritis significantly aggravated cartilage destruction and inflammation, characterized by a massive influx of PMNs, which adhered to the cartilage surface. Although IL-17 overexpression increased FcgammaR messenger RNA levels in the synovium, in vitro stimulation of macrophages and PMNs revealed that, in contrast to IFNgamma, IL-17 did not directly regulate FcgammaR expression. Despite similar inflammation in AdIL-17-enhanced IC-mediated arthritis in gamma-chain(-/-) mice and wild-type controls, severe cartilage destruction and PMN adherence were completely absent in gamma-chain(-/-) mice.
  
  
  CONCLUSIONS
  Our findings indicate that IL-17-mediated aggravation of cartilage destruction in IC-mediated arthritis is FcgammaR dependent. However, in contrast to IFNgamma, which directly up-regulates FcgammaR expression on macrophages and PMNs, IL-17 enhances cartilage destruction by increasing the local amount of FcgammaR-bearing neutrophils.
authors.affiliation: Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
authors.forename: Lilyanne C
authors.initials: LC
authors.lastname: Grevers
authors.forename: Peter L E M
authors.initials: PL
authors.lastname: van Lent
authors.forename: Marije I
authors.initials: MI
authors.lastname: Koenders
authors.forename: Birgitte
authors.initials: B
authors.lastname: Walgreen
authors.forename: Annet W
authors.initials: AW
authors.lastname: Sloetjes
authors.forename: Falk
authors.initials: F
authors.lastname: Nimmerjahn
authors.forename: J
authors.initials: J
authors.lastname: Sjef Verbeek
authors.forename: Wim B
authors.initials: WB
authors.lastname: van den Berg
mesh_terms: D000276:Adjuvants, Immunologic; D000818:Animals; D001169:Arthritis, Experimental / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D015415:Biomarkers / Q000378:metabolism; D002358:Cartilage, Articular / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D002460:Cell Line; D019902:Chondrocytes / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D019084:Fluorescent Antibody Technique, Indirect; D006614:Hindlimb; D007371:Interferon-gamma / Q000378:metabolism* / Q000494:pharmacology; D020381:Interleukin-17 / Q000378:metabolism* / Q000494:pharmacology; D007596:Joints / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009336:Necrosis; D009504:Neutrophils / Q000187:drug effects / Q000378:metabolism; D017452:Receptors, IgG / Q000235:genetics / Q000378:metabolism*; D013583:Synovial Membrane / Q000187:drug effects / Q000378:metabolism*
chemical_list: D000276:Adjuvants, Immunologic; D015415:Biomarkers; D020381:Interleukin-17; D017452:Receptors, IgG; D007371:Interferon-gamma