Prion pathogenesis in the absence of Toll-like receptor signalling.
To reach the brain from peripheral sites, prions must colonize various cell types within the lymphoreticular compartment. However, no prion entry receptors are yet known. Toll-like receptors (TLRs) are pattern-recognition receptors that bind a multitude of pathogens and are therefore candidates as effectors of prion entry. Moreover, injection of unmethylated CpG oligodinucleotides, which stimulate TLR9, has been reported to delay peripherally initiated scrapie. We therefore studied prion infection in MyD88(-/-) mice, which are defective in TLR signalling. Despite subtle defects in splenic microarchitecture, MyD88(-/-) mice challenged intraperitoneally or intracerebrally were fully susceptible to disease and died of scrapie after similar incubation times to those of wild-type mice. Splenic infectivity titres rose to similar levels with the same kinetics, and brains showed similar histopathological changes. TLR signalling therefore does not have any major role in prion pathogenesis, and the protective effect of TLR stimulation is unlikely to result from direct interactions with prions.
Prinz
Marco
M
University Hospital of Zürich, Zürich, Switzerland.
Heikenwalder
Mathias
M
Schwarz
Petra
P
Takeda
Kiyoshi
K
Akira
Shizuo
S
Aguzzi
Adriano
A
D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D000943:Antigens, Differentiation / Q000235:genetics / Q000378:metabolism; D001921:Brain / Q000378:metabolism / Q000473:pathology; D020566:Dendritic Cells, Follicular / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000378:metabolism*; D051379:Mice; D053594:Myeloid Differentiation Factor 88; D018620:PrPSc Proteins / Q000378:metabolism; D011328:Prions / Q000472:pathogenicity*; D011956:Receptors, Cell Surface / Q000378:metabolism*; D011971:Receptors, Immunologic / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D012608:Scrapie / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D013154:Spleen / Q000378:metabolism / Q000473:pathology; D051193:Toll-Like Receptors
D048868:Adaptor Proteins, Signal Transducing; D000943:Antigens, Differentiation; D008562:Membrane Glycoproteins; C507780:Myd88 protein, mouse; D053594:Myeloid Differentiation Factor 88; D018620:PrPSc Proteins; D011328:Prions; D011956:Receptors, Cell Surface; D011971:Receptors, Immunologic; D051193:Toll-Like Receptors