title: Peptide p5 binds both heparinase-sensitive glycosaminoglycans and fibrils in patient-derived AL amyloid extracts.
abstract: In previously published work, we have described heparin-binding synthetic peptides that preferentially recognize amyloid deposits in a mouse model of reactive systemic (AA) amyloidosis and can be imaged by using positron and single photon emission tomographic imaging. We wanted to extend these findings to the most common form of visceral amyloidosis, namely light chain (AL); however, there are no robust experimental animal models of AL amyloidosis. To further define the binding of the lead peptide, p5, to AL amyloid, we characterized the reactivity in vitro of p5 with in situ and patient-derived AL amyloid extracts which contain both hypersulfated heparan sulfate proteoglycans as well as amyloid fibrils. Histochemical staining demonstrated that the peptide specifically localized with tissue-associated AL amyloid deposits. Although we anticipated that p5 would undergo electrostatic interactions with the amyloid-associated glycosaminoglycans expressing heparin-like side chains, no significant correlation between peptide binding and glycosaminoglycan content within amyloid extracts was observed. In contrast, following heparinase I treatment, although overall binding was reduced, a positive correlation between peptide binding and amyloid fibril content became evident. This interaction was further confirmed using synthetic light chain fibrils that contain no carbohydrates. These data suggest that p5 can bind to both the sulfated glycosaminoglycans and protein fibril components of AL amyloid. Understanding these complex electrostatic interactions will aid in the optimization of synthetic peptides for use as amyloid imaging agents and potentially as therapeutics for the treatment of amyloid diseases.
authors.affiliation: Department of Medicine, University of Tennessee Graduate School of Medicine, 1924 Alcoa Highway, Knoxville, TN 37922, USA.
authors.forename: Emily B
authors.initials: EB
authors.lastname: Martin
authors.forename: Angela
authors.initials: A
authors.lastname: Williams
authors.forename: Eric
authors.initials: E
authors.lastname: Heidel
authors.forename: Sallie
authors.initials: S
authors.lastname: Macy
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Kennel
authors.forename: Jonathan S
authors.initials: JS
authors.lastname: Wall
mesh_terms: D000423:Alcian Blue / Q000737:chemistry / Q000494:pharmacology; D000682:Amyloid / Q000378:metabolism*; D000686:Amyloidosis / Q000378:metabolism*; D052160:Benzothiazoles; D002241:Carbohydrates / Q000737:chemistry; D006025:Glycosaminoglycans / Q000737:chemistry* / Q000378:metabolism; D006493:Heparin / Q000737:chemistry; D019763:Heparin Lyase / Q000737:chemistry*; D006801:Humans; D010455:Peptides / Q000737:chemistry / Q000494:pharmacology*; D011485:Protein Binding; D055672:Static Electricity; D013844:Thiazoles / Q000494:pharmacology
chemical_list: D000682:Amyloid; D052160:Benzothiazoles; D002241:Carbohydrates; D006025:Glycosaminoglycans; D010455:Peptides; D013844:Thiazoles; C035222:amyloid protein AL; C009462:thioflavin T; D006493:Heparin; D019763:Heparin Lyase; D000423:Alcian Blue