Lack of TAR-DNA binding protein-43 (TDP-43) pathology in human prion diseases

Aims: TAR‐DNA binding protein‐43 (TDP‐43) is the major ubiquitinated protein in the aggregates in frontotemporal dementia with ubiquitin‐positive, tau‐negative inclusions and motor neurone disease. Abnormal TDP‐43 immunoreactivity has also been described in Alzheimer's disease, Lewy body diseases and Guam parkinsonism–dementia complex. We therefore aimed to determine whether there is TDP‐43 pathology in human prion diseases, which are characterised by variable deposition of prion protein (PrP) aggregates in the brain as amyloid plaques or more diffuse deposits. Material and methods: TDP‐43, ubiquitin and PrP were analysed by immunohistochemistry and double‐labelling immunofluorescence, in sporadic, acquired and inherited forms of human prion disease. Results: Most PrP plaques contained ubiquitin, while synaptic PrP deposits were not associated with ubiquitin. No abnormal TDP‐43 inclusions were identified in any type of prion disease case, and TDP‐43 did not co‐localize with ubiquitin‐positive PrP plaques or with diffuse PrP aggregates. Conclusions: These data do not support a role for TDP‐43 in prion disease pathogenesis and argue that TDP‐43 inclusions define a distinct group of neurodegenerative disorders.