Amyloid-Beta Radiotracer [18F]BF-227 Does Not Bind to Cytoplasmic Glial Inclusions of Postmortem Multiple System Atrophy Brain Tissue

Contrast Media Mol Imaging. 2018 Feb 6:2018:9165458. doi: 10.1155/2018/9165458. eCollection 2018.

Abstract

The accumulation of aggregated alpha-synuclein (α-syn) in multiple brain regions is a neuropathological hallmark of synucleinopathies. Multiple system atrophy (MSA) is a synucleinopathy characterized by the predominant cerebral accumulation of aggregated α-syn as cytoplasmic glial inclusions (CGI). A premortem diagnosis tool would improve early diagnosis and help monitoring disease progression and therapeutic efficacy. One Positron Emission Tomography (PET) study suggested [11C]BF-227 as a promising radiotracer for monitoring intracellular α-syn deposition in MSA patients. We sought to confirm the binding of this radiotracer to α-syn using state-of-the-art autoradiography. Medulla sections were obtained from 9 MSA patients and 9 controls (London Neurodegenerative Diseases Brain Bank). [18F]BF-227, chemically identical to [11C]BF-227, was used at nanomolar concentrations to perform in vitro autoradiography assays. Autoradiograms were superimposed on fluorescent staining from the conformational anti-α-syn antibody 5G4 and quantified after immunofluorescence-driven definition of regions of interest. Autoradiography showed no specific signals in MSA patients in comparison to controls despite widespread pathology detected by immunofluorescence. Autoradiography does not support a significant binding of [18F]BF-227 to CGI at concentrations typically achieved in PET experiments.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Benzoxazoles* / pharmacokinetics
  • Benzoxazoles* / pharmacology
  • Brain* / diagnostic imaging
  • Brain* / metabolism
  • Female
  • Fluorine Radioisotopes* / pharmacokinetics
  • Fluorine Radioisotopes* / pharmacology
  • Humans
  • Immunohistochemistry
  • Male
  • Multiple System Atrophy* / diagnostic imaging
  • Multiple System Atrophy* / metabolism
  • Neuroglia / metabolism*
  • Positron-Emission Tomography*
  • Thiazoles* / pharmacokinetics
  • Thiazoles* / pharmacology
  • alpha-Synuclein / metabolism*

Substances

  • 2-(2-(2-dimethylaminothiazol-5-yl)ethenyl)-6-(2-(fluoro)ethoxy)benzoxazole
  • Benzoxazoles
  • Fluorine Radioisotopes
  • SNCA protein, human
  • Thiazoles
  • alpha-Synuclein
  • Fluorine-18