Bioluminescence Imaging of Neuroinflammation in Transgenic Mice After Peripheral Inoculation of Alpha-Synuclein Fibrils

Sara Breid; Maria E. Bernis; Julius B. Tachu; Maria C. Garza; Holger Wille; Gültekin Tamgüney

doi:10.3791/55503

Method Article

Bioluminescence Imaging of Neuroinflammation in Transgenic Mice After Peripheral Inoculation of Alpha-Synuclein Fibrils

8.3K views

⸱

DOI:

10.3791/55503

⸱

April 13th, 2017

Sara Breid¹ , Maria E. Bernis¹ , Julius B. Tachu¹ , Maria C. Garza² , Holger Wille² , Gültekin Tamgüney¹

¹German Center for Neurodegenerative Diseases (DZNE), ²Centre for Prions and Protein Folding Diseases & Department of Biochemistry, University of Alberta

Summary

Peripheral injection of alpha-synuclein fibrils into the peritoneum or tongue of Tg(M83^+/-:Gfap-luc^+/-) mice, which express human alpha-synuclein with the familial A53T mutation and firefly luciferase, can induce neuropathology, including neuroinflammation, in their central nervous system.

Abstract

To study the prion-like behavior of misfolded alpha-synuclein, mouse models are needed that allow fast and simple transmission of alpha-synuclein prionoids, which cause neuropathology within the central nervous system (CNS). Here we describe that intraglossal or intraperitoneal injection of alpha-synuclein fibrils into bigenic Tg(M83^+/-:Gfap-luc^+/-) mice, which overexpress human alpha-synuclein with the A53T mutation from the prion protein promoter and firefly luciferase from the promoter for glial fibrillary acidic protein (Gfap), is sufficient to induce neuropathologic disease. In comparison to homozygous Tg(M83^+/+) mice that develop severe neurologic symptoms beginning at an age of 8 months, heterozygous Tg(M83^+/-:Gfap-luc^+/-) animals remain free of spontaneous disease until they reach an age of 22 months. Interestingly, injection of alpha-synuclein fibrils via the intraperitoneal route induced neurologic disease with paralysis in four of five Tg(M83^+/-:Gfap-luc^+/-) mice with a median incubation time of 229 ±17 days. Diseased animals showed severe deposits of phosphorylated alpha-synuclein in their brains and spinal cords. Accumulations of alpha-synuclein were sarkosyl-insoluble and colocalized with ubiquitin and p62, and were accompanied by an inflammatory response resulting in astrocytic gliosis and microgliosis. Surprisingly, inoculation of alpha-synuclein fibrils into the tongue was less effective in causing disease with only one of five injected animals showing alpha-synuclein pathology after 285 days. Our findings show that inoculation via the intraglossal route and more so via the intraperitoneal route is suitable to induce neurologic illness with relevant hallmarks of synucleinopathies in Tg(M83^+/-:Gfap-luc^+/-) mice. This provides a new model for studying prion-like pathogenesis induced by alpha-synuclein prionoids in greater detail.

Introduction

There is growing evidence that alpha-synuclein has characteristics that are similar to those of the prion protein, particularly in its capacity to self-seed and propagate misfolding between cells and along neuronal pathways. This property of alpha-synuclein is also referred to as 'prion-like' or 'prionoid', and is supported by observations in transplantation experiments, which suggest the transmissibility of misfolded alpha-synuclein from diseased neurons to newly transplanted healthy neurons¹^,²^,³^,⁴. Also direct injection of ....