title: Serum level of soluble CX3CL1/fractalkine is elevated in patients with polymyositis and dermatomyositis, which is correlated with disease activity.
abstract: BACKGROUND
  Polymyositis (PM) and dermatomyositis (DM) are chronic inflammatory muscle diseases, in which chemokines are thought to contribute to inflammatory cell migration into muscle. In this study, we retrospectively analyzed the expressions of CX3CL1/fractalkine and its corresponding receptor, CX3CR1, in muscle and lung with interstitial lung disease (ILD) of PM patients and DM patients, and determined the correlation between serum soluble CX3CL1 level and disease activity.
  
  
  METHODS
  Expressions of CX3CL1 and CX3CR1 in muscle and lung tissue were analyzed by immunohistochemistry. Serum CX3CL1 concentrations were measured by ELISA. For evaluation of patients' disease activity, serum creatinine kinase, manual muscle testing, and the alveolar-arterial oxygen pressure difference were used independently.
  
  
  RESULTS
  CX3CL1 was expressed on infiltrated mononuclear cells and endothelial cells in muscle affected by PM and DM and in lung with ILD, whereas CX3CR1 was expressed on some CD4+ T cells, a majority of CD8+ T cells, and most macrophages in muscle, and on infiltrated mononuclear cells in the lung. Serum soluble CX3CL1 was significantly higher in PM patients and DM patients than in healthy controls. The CX3CL1 level was correlated with serum creatinine kinase and manual muscle testing score. In patients with PM and DM with ILD, serum CX3CL1 was also correlated with alveolar-arterial oxygen pressure difference. Furthermore, CX3CL1 was significantly decreased after conventional treatment.
  
  
  CONCLUSIONS
  The interaction between CX3CL1 and CX3CR1 might contribute to the inflammatory cell infiltration into affected muscle and lung with ILD in PM patients and DM patients. Serum CX3CL1 level could be a surrogate marker of disease activity.
authors.affiliation: Department of Medicine and Rheumatology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8519, Japan.
authors.forename: Fumihito
authors.initials: F
authors.lastname: Suzuki
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Kubota
authors.forename: Yasunari
authors.initials: Y
authors.lastname: Miyazaki
authors.forename: Kinya
authors.initials: K
authors.lastname: Ishikawa
authors.forename: Masashi
authors.initials: M
authors.lastname: Ebisawa
authors.forename: Shunsei
authors.initials: S
authors.lastname: Hirohata
authors.forename: Takashi
authors.initials: T
authors.lastname: Ogura
authors.forename: Hidehiro
authors.initials: H
authors.lastname: Mizusawa
authors.forename: Toshio
authors.initials: T
authors.lastname: Imai
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Miyasaka
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Nanki
mesh_terms: D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000097:blood; D054428:Chemokine CX3CL1 / Q000097:blood*; D003882:Dermatomyositis / Q000097:blood* / Q000175:diagnosis*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017285:Polymyositis / Q000097:blood* / Q000175:diagnosis*; D012189:Retrospective Studies; D012995:Solubility
chemical_list: D015415:Biomarkers; C515538:CX3CL1 protein, human; D054428:Chemokine CX3CL1