Autophagy Contributes to Widespread Neuronal Degeneration in Hamsters Infected with the Echigo-1 Strain of Creutzfeldt-Jakob Disease and Mice Infected with the Fujisaki Strain of Gerstmann-Sträussler-Scheinker (GSS) Syndrome

Abstract

The authors report here robust autophagy observed by electron microscopy in both the Echigo-1 strain of Creutzfeldt-Jakob disease in hamsters and the Fujisaki strain of Gerstmann-Sträussler-Scheinker disease in mice. In both models, autophagic vacuoles were observed in several cellular compartments. In neuronal cell bodies, autophagic vacuoles of different size were seen. The cytoplasm of some neurons also contained semicircular cisterns equivalent to an early autophasophore. The major target of autophagy was dystrophic neurites, i.e., enlarged neuritic processes—mostly dendrites but also axonal terminals and preterminals. They contained numerous double- or multiple-membrane-bound autophagosomes or autophagolysosomes and large multivesicular bodies. Multivesicular bodies were also observed within autophagic vacuoles, and large multivesicular bodies were seen within synaptic terminals. Some dystrophic neurites was filled almost completely with multivesicular bodies; the latter were occasionally confluent. The authors conclude that autophagy is an important part of neuropathology in prion disease. They also suggest that spongiform vacuoles, a hallmark for the whole group of prion diseases, may in reality originate from autophagic vacuoles.