title: Cyr61 is involved in neutrophil infiltration in joints by inducing IL-8 production by fibroblast-like synoviocytes in rheumatoid arthritis.
abstract: BACKGROUND
  It is well known that neutrophils play very important roles in the development of rheumatoid arthritis (RA) and interleukin (IL)-8 is a critical chemokine in promoting neutrophil migration. We previously showed that increased production of Cyr61 by fibroblast-like synoviocytes (FLS) in RA promotes FLS proliferation and Th17 cell differentiation, thus Cyr61 is a pro-inflammatory factor in RA pathogenesis. In this study, we explored the role of Cyr61 in neutrophil migration to the joints of RA patients.
  
  
  METHODS
  RA FLS were treated with Cyr61 and IL-8 expression was analyzed by real-time PCR and ELISA. The migration of neutrophils recruited by the culture supernatants was determined by the use of a chemotaxis assay. Mice with collagen-induced arthritis (CIA) were treated with anti-Cyr61 monoclonal antibodies (mAb), or IgG1 as a control. Arthritis severity was determined by visual examination of the paws and joint destruction was determined by hematoxylin-eosin (H&E) staining. Signal transduction pathways in Cyr61-induced IL-8 production were investigated by real-time PCR, western blotting, confocal microscopy, luciferase reporter assay or chromatin immunoprecipitation (ChIP) assay.
  
  
  RESULTS
  We found that Cyr61 induced IL-8 production by RA FLS in an IL-1β and TNF-α independent pathway. Moreover, we identified that Cyr61-induced IL-8-mediated neutrophil migration in vitro. Using a CIA animal model, we found that treatment with anti-Cyr61 mAb led to a reduction in MIP-2 (a counterpart of human IL-8) expression and decrease in neutrophil infiltration, which is consistent with an attenuation of inflammation in vivo. Mechanistically, we showed that Cyr61 induced IL-8 production in FLS via AKT, JNK and ERK1/2-dependent AP-1, C/EBPβ and NF-κB signaling pathways.
  
  
  CONCLUSIONS
  Our results here reveal a novel role of Cyr61 in the pathogenesis of RA. It promotes neutrophil infiltration via up-regulation of IL-8 production in FLS. Taken together with our previous work, this study provides further evidence that Cyr61 plays a key role in the vicious cycle formed by the interaction between infiltrating neutrophils, proliferated FLS and activated Th17 cells in the development of RA.
authors: Xianjin
authors: X
authors: Zhu
authors: Lianbo
authors: L
authors: Xiao
authors: Rongfen
authors: R
authors: Huo
authors: Jie
authors: J
authors: Zhang
authors: Jinpiao
authors: J
authors: Lin
authors: Jun
authors: J
authors: Xie
authors: Songtao
authors: S
authors: Sun
authors: Yong
authors: Y
authors: He
authors: Yue
authors: Y
authors: Sun
authors: Zhou
authors: Z
authors: Zhou
authors: Baihua
authors: B
authors: Shen
authors: Ningli
authors: N
authors: Li
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D001169:Arthritis, Experimental / Q000276:immunology / Q000378:metabolism; D001172:Arthritis, Rheumatoid / Q000276:immunology*; D015153:Blotting, Western; D047369:Chromatin Immunoprecipitation; D055515:Cysteine-Rich Protein 61 / Q000276:immunology* / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005347:Fibroblasts / Q000276:immunology / Q000378:metabolism; D005434:Flow Cytometry; D006801:Humans; D007154:Immune System Diseases / Q000276:immunology*; D016209:Interleukin-8 / Q000096:biosynthesis*; D007960:Leukocyte Disorders / Q000276:immunology*; D008297:Male; D051379:Mice; D008811:Mice, Inbred DBA; D018613:Microscopy, Confocal; D008875:Middle Aged; D020556:Neutrophil Infiltration / Q000276:immunology*; D060888:Real-Time Polymerase Chain Reaction; D013583:Synovial Membrane / Q000276:immunology / Q000378:metabolism
chemical_list: C501848:CCN1 protein, human; D055515:Cysteine-Rich Protein 61; D016209:Interleukin-8