title: A novel method for quantifying peripheral tissue amyloid load by using the radiolabeled amyloidophilic peptide, p5.
abstract: Quantitation of peripheral amyloid deposits by non-invasive molecular imaging can be useful for diagnosis, prognostication and monitoring response to therapy. In order to obtain reliable quantitative data, it is necessary to show a linear positive correlation between the uptake of the molecular probe and the tissue amyloid load. The transgenic H-2/IL-6 mouse model of AA amyloidosis was used to generate animals with varied stages of visceral amyloid disease. The mice were injected with 125I-labeled peptide p5 and tissues analyzed 2 h post-injection using Congo red (CR) staining, radioisotope biodistribution and micro-autoradiography (ARG). Micro-ARG confirmed that 125I-p5 was deposited at all amyloid deposits and sites of Congophilia but not at amyloid-free sites within the tissues evaluated. Furthermore, biodistribution studies revealed that the amount of 125I deposited in liver and spleen correlated with the amount of CR birefringence (expressed as 0-4+ or as tissue area [µm2]) in these tissues with correlation coefficients of r > 0.7 (p < 10(-6)). Deposition of 125I-p5 is a quantitative measure of the amount of AA amyloid in liver and spleen in this mouse model. The p5 peptide has potential as a quantitative amyloid imaging agent in human disease.
authors: Department of Medicine, University of Tennessee Graduate School of Medicine, Knoxville, TN 37920, USA. jwall@utmck.edu
authors: Jonathan S
authors: JS
authors: Wall
authors: Tina
authors: T
authors: Richey
authors: Sally
authors: S
authors: Macy
authors: Eric
authors: E
authors: Heidel
authors: Craig
authors: C
authors: Wooliver
authors: Stephen J
authors: SJ
authors: Kennel
mesh_terms: D000595:Amino Acid Sequence; D000682:Amyloid / Q000032:analysis*; D000686:Amyloidosis / Q000378:metabolism* / Q000473:pathology; D000818:Animals; D007457:Iodine Radioisotopes; D008099:Liver / Q000378:metabolism* / Q000473:pathology; D051379:Mice; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000378:metabolism / Q000493:pharmacokinetics*; D010446:Peptide Fragments / Q000378:metabolism / Q000493:pharmacokinetics*; D013154:Spleen / Q000378:metabolism* / Q000473:pathology
chemical_list: D000682:Amyloid; D007457:Iodine Radioisotopes; D009419:Nerve Tissue Proteins; D010446:Peptide Fragments; C553404:p5 protein, human