PET of Brain Prion Protein Amyloid in Gerstmann–Sträussler–Scheinker Disease

Authors


  • Contributors: VK, BG, MRF, MB, S-CH, GWS and JRB participated in the design of the study. VK, BG, MRF, KM, FE, JL, NS, GWS and JRB were instrumental in performing the imaging study. VK, S-CH, KPW and JRB developed image analysis methodology and analyzed the imaging data. MB, GR, LMS and AP performed in vitro tissue labeling experiments and analysis. VK, BG, MRF, MG, KM, S-CH, JRM, PP, LMS, PS, GWS and JRB evaluated the data. VK, BG, MB and JRB contributed to the development of the first draft. VK and JRB developed the final draft. All authors contributed to the writing and the revision of this paper, and approved the final version.

Jorge R. Barrio, PhD, Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095-6948 (E-mail: jbarrio@mednet.ucla.edu)

Abstract

In vivo amyloid PET imaging was carried out on six symptomatic and asymptomatic carriers of PRNP mutations associated with the Gerstmann–Sträussler–Scheinker (GSS) disease, a rare familial neurodegenerative brain disorder demonstrating prion amyloid neuropathology, using 2-(1-{6-[(2-[F-18]fluoroethyl)(methyl)amino]-2-naphthyl}ethylidene)malononitrile ([F-18]FDDNP). 2-Deoxy-2-[F-18]fluoro-d-glucose PET ([F-18]FDG) and magnetic resonance imaging (MRI) scans were also performed in each subject.

Increased [F-18]FDDNP binding was detectable in cerebellum, neocortex and subcortical areas of all symptomatic gene carriers in close association with the experienced clinical symptoms. Parallel glucose metabolism ([F-18]FDG) reduction was observed in neocortex, basal ganglia and/or thalamus, which supports the close relationship between [F-18]FDDNP binding and neuronal dysfunction. Two asymptomatic gene carriers displayed no cortical [F-18]FDDNP binding, yet progressive [F-18]FDDNP retention in caudate nucleus and thalamus was seen at 1- and 2-year follow-up in the older asymptomatic subject. In vitro FDDNP labeling experiments on brain tissue specimens from deceased GSS subjects not participating in the in vivo studies indicated that in vivo accumulation of [F-18]FDDNP in subcortical structures, neocortices and cerebellum closely related to the distribution of prion protein pathology. These results demonstrate the feasibility of detecting prion protein accumulation in living patients with [F-18]FDDNP PET, and suggest an opportunity for its application to follow disease progression and monitor therapeutic interventions.

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