title: In vivo imaging of experimental arthritis with near-infrared fluorescence.
abstract: OBJECTIVE
  To visualize early experimental arthritis with near-infrared fluorescence (NIRF) imaging in a murine model of antigen-induced arthritis (AIA).
  
  
  METHODS
  The target of NIRF was the F4/80 antigen present on the surface of macrophages infiltrating the inflamed synovial membrane. Imaging was performed using anti-F4/80 monoclonal antibodies (mAb) labeled with Cy5.5 fluorochrome. On day 7 of AIA, 6 mice received an intravenous (IV) injection of labeled mAb; control AIA mice (n = 6) received an IV injection of Cy5.5-labeled isotype control antibody. NIRF imaging was performed before injection (baseline) and until 72 hours thereafter. Histologic evaluation of arthritis severity and immunohistochemical assessment of F4/80 antigen density were also performed on day 7.
  
  
  RESULTS
  NIRF imaging showed an accumulation of fluorochrome probes in the inflamed knee joints and, to a lesser extent, in the contralateral (nonarthritic) knee joints. The signal induced by mAb F4/80 was clearly higher than that generated by the isotype control. Accumulation of fluorochrome probes in the joints was confirmed histologically by confocal laser scanning microscopy.
  
  
  CONCLUSIONS
  The use of fluorochromes allows imaging of arthritis in the near-infrared range. Accumulation in the contralateral, nonarthritic knee joints can be explained by the presence of sentinel macrophages in normal synovium or by a mild contralateral response due to systemic activation or neurogenic mechanisms.
authors.affiliation: Institute of Diagnostic and Interventional Radiology, Fredrich Schiller University Jena, Jena, Germany. andreas.hansch@med.uni-jena.de
authors.forename: Andreas
authors.initials: A
authors.lastname: Hansch
authors.forename: Oliver
authors.initials: O
authors.lastname: Frey
authors.forename: Dieter
authors.initials: D
authors.lastname: Sauner
authors.forename: Ingrid
authors.initials: I
authors.lastname: Hilger
authors.forename: Michael
authors.initials: M
authors.lastname: Haas
authors.forename: Ansgar
authors.initials: A
authors.lastname: Malich
authors.forename: Rolf
authors.initials: R
authors.lastname: Bräuer
authors.forename: Werner A
authors.initials: WA
authors.lastname: Kaiser
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal; D000943:Antigens, Differentiation / Q000276:immunology; D001169:Arthritis, Experimental / Q000175:diagnosis*; D002232:Carbocyanines / Q000493:pharmacokinetics; D005470:Fluorometry; D007719:Knee Joint / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018613:Microscopy, Confocal; D019265:Spectroscopy, Near-Infrared
chemical_list: D000911:Antibodies, Monoclonal; D000943:Antigens, Differentiation; C098793:CY5.5 cyanine dye; D002232:Carbocyanines; C036763:monocyte-macrophage differentiation antigen