Prion Strain Differences in Accumulation of PrPSc on Neurons and Glia Are Associated with Similar Expression Profiles of Neuroinflammatory Genes: Comparison of Three Prion Strains - Fig 3

<p><b>Cell-type associations of PrPSc in thalamus after microinjection with scrapie strains 22L, 40 dpi (A-D), RML, 60 dpi (E-H) and ME7, 60 dpi (I-L)</b>. PrPSc was detected by IHC with monoclonal antibody D13, and slides were also dual-stained with a second antibody to detect neurons (NeuN), astroglia (GFAP), microglia (Iba1) and oligodendroglia (Ol2), as described in methods. (A) Several cells positive for both 22L PrPSc and GFAP (arrows) are noted. Inset shows a PrPSc-positive stellate cell at 20 dpi that was GFAP-negative. (B) 22L PrPSc-positive cells negative for Neu-N (arrows) are shown. Arrowhead shows PrPSc on a small blood vessel. Blue arrow shows PrPSc in neuropil not associated with any cell body. (C) One cell with 22L PrPSc and Iba1 co-association is shown (blue arrow). Several PrPSc-positive cells negative for Iba1 are also seen (black arrows). (D) Cells positive for 22L PrPSc and Olig2 (Ol2) (arrows) plus neuropil PrPSc (arrowhead) is seen. (E) RML PrPSc co-associates with GFAP-positive astroglia (arrows). (F) Intense RML PrPSc staining (arrows) is seen around Neu-N-negative cells with pale blue nuclei. Diffuse PrPSc staining is seen in neuropil background and is often adjacent to Neu-N-positive neurons, therefore possible association with neurons is difficult to exclude. (G) Lack of co-localization of RML PrPSc and Iba1. PrPSc-positive cells (arrows) are distinguishable from Iba1-positive cells (arrowhead). (H) Several cells are co-stained for RML PrPSc and Olig2 (arrows). Less dense PrPSc covers much of background neuropil. (I) After ME7 infection shows GFAP-positive astrocytes near larger PrPSc deposits (black arrows) in neuropil, but most astrocytes are PrPSc-negative (blue arrow). (J) Neu-N-positive neuron with ME7 PrPSc co-localization (arrow) on ipsilateral side. Additional PrPSc staining in larger aggregates (arrowheads) appears in neuropil. (K) No accumulation of ME7 PrPSc on Iba1-positive cells (blue arrow). PrPSc was seen in neuropil (black arrow) and possibly associated with large unstained neurons (arrowhead). (L) Large ME7 PrPSc aggregates in neuropil (arrows) with no evidence for accumulation on cells positive for Olig2 (arrowhead). Scale bar shown in panel A is 50 μm and applies to all panels.</p>