title: The pattern recognition reagents RAGE VC1 and peptide p5 share common binding sites and exhibit specific reactivity with AA amyloid in mice.
abstract: In the US, there remains a need to develop a clinical method for imaging amyloid load in patients with systemic, visceral amyloidosis. The receptor for advanced glycation end products (RAGE), which exists as a transmembrane receptor and soluble variant, is found associated with a number of amyloid deposits in man. It is unclear whether amyloid-associated RAGE is the membrane or soluble form; however, given the affinity of RAGE for amyloid, we have examined the ability of soluble RAGE VC1 to specifically localize with systemic AA amyloid in mice. We further compared the reactivity of RAGE VC1 with that of the synthetic, amyloid-reactive peptide p5.
  
  
  METHODS
  Binding of radiolabeled RAGE VC1 and p5 to synthetic amyloid fibrils was evaluated using in vitro "pulldown" assays in the presence or absence of RAGE ligands. Radioiodinated RAGE VC1 and technetium-99 m-labeled p5 were studied in mice with systemic AA amyloidosis using dual-energy SPECT/CT imaging, biodistribution and microautoradiography.
  
  
  RESULTS
  Soluble RAGE VC1 competed with radioiodinated peptide p5 for binding to rVλ6Wil, Aβ (1-40) and IAPP fibrils but not with the higher affinity peptide, p5R. Pre-incubation with AGE-BSA abrogated binding of VC1 and p5 to rVλ6Wil fibrils. Dual-energy SPECT/CT images and quantitative tissue biodistribution data showed that soluble RAGE VC1 specifically bound AA amyloid-laden organs in mice as effectively as peptide p5. Furthermore, microautoradiography confirmed that RAGE VC1 bound specifically to areas of Congo red-positive amyloid in mouse tissues but not in comparable tissues from control WT mice.
  
  
  CONCLUSIONS
  Soluble RAGE VC1 and peptide p5 have similar ligand binding properties and specifically localize with visceral AA amyloid deposits in mice.
authors.affiliation: a Department of Medicine and.|b Department of Radiology , University of Tennessee, Graduate School of Medicine , Knoxville , TN , USA .
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Kennel
authors.affiliation: a Department of Medicine and.
authors.forename: Angela
authors.initials: A
authors.lastname: Williams
authors.affiliation: b Department of Radiology , University of Tennessee, Graduate School of Medicine , Knoxville , TN , USA .
authors.forename: Alan
authors.initials: A
authors.lastname: Stuckey
authors.affiliation: a Department of Medicine and.
authors.forename: Tina
authors.initials: T
authors.lastname: Richey
authors.affiliation: a Department of Medicine and.
authors.forename: Craig
authors.initials: C
authors.lastname: Wooliver
authors.affiliation: c Departments of Biochemistry and Chemistry , Center for Structural Biology, Vanderbilt University , Nashville , TN , USA , and.
authors.forename: Walter
authors.initials: W
authors.lastname: Chazin
authors.affiliation: d Department of Medicine , University of Tennessee School of Medicine , Memphis , TN , USA.
authors.forename: David A
authors.initials: DA
authors.lastname: Stern
authors.affiliation: a Department of Medicine and.
authors.forename: Emily B
authors.initials: EB
authors.lastname: Martin
authors.affiliation: a Department of Medicine and.|b Department of Radiology , University of Tennessee, Graduate School of Medicine , Knoxville , TN , USA .
authors.forename: Jonathan S
authors.initials: JS
authors.lastname: Wall
mesh_terms: D000686:Amyloidosis / Q000000981:diagnostic imaging* / Q000378:metabolism; D000818:Animals; D001667:Binding, Competitive; D007457:Iodine Radioisotopes / Q000737:chemistry / Q000493:pharmacokinetics; D008807:Mice, Inbred BALB C; D008822:Mice, Transgenic; D010455:Peptides / Q000737:chemistry / Q000493:pharmacokinetics; D011485:Protein Binding; D015900:Radiography, Dual-Energy Scanned Projection; D019275:Radiopharmaceuticals / Q000737:chemistry / Q000493:pharmacokinetics; D000067759:Receptor for Advanced Glycation End Products / Q000737:chemistry; D011994:Recombinant Proteins / Q000737:chemistry / Q000493:pharmacokinetics; D000685:Serum Amyloid A Protein / Q000737:chemistry / Q000378:metabolism*; D013667:Technetium / Q000737:chemistry / Q000493:pharmacokinetics; D014018:Tissue Distribution; D014057:Tomography, X-Ray Computed
chemical_list: D007457:Iodine Radioisotopes; D010455:Peptides; C000612167:RAGE VC1 protein; D019275:Radiopharmaceuticals; D000067759:Receptor for Advanced Glycation End Products; D011994:Recombinant Proteins; D000685:Serum Amyloid A Protein; C000612168:p5 amyloid-reactive peptide; D013667:Technetium
keywords: AA amyloid; AGE-BSA; SPECT imaging; molecular imaging; peptide p5; receptor for advanced glycation end products