Type I interferon protects neurons from prions in in vivo models

Ishibashi, Daisuke; Homma, Takujiro; Nakagaki, Takehiro; Fuse, Takayuki; Sano, Kazunori; Satoh, Katsuya; Mori, Tsuyoshi; Atarashi, Ryuichiro; Nishida, Noriyuki

To investigate whether RO8191 functions in the brain, we performed a blood-brain barrier permeability assay using the BBB Kit TM in vitro. The blood-brain barrier permeability coefficient (Papp), which indicates the ability of the compound to translocate from blood vessels to the brain, was measured using the BBB Kit TM (Pervin et al., 2017) . After 60 min, RO8191 exhibited a significantly higher blood-brain barrier permeability coefficient (43.94 AE 7.29) than sodium fluorescein (F-Na), the negative control (2.66 AE 0.78) (Fig. 7A) . Moreover, to confirm the levels of RO8191 in the tissues of the animal model, we measured the concentration of RO8191 in the brains and spleens of prion-infected mice with RO8191 treatment at immortalized MEFs from wild-type and Ifnar1 À/À mice after prion infection with 6 Â 10 À3 to 1.5 Â 10 À1 % 22 L-brain homogenate (BH). Graphs show quantification of PrP Sc levels in wild-type (black) and Ifnar1 À/À (white) cells. *P 5 0.05 versus wild-type. (B) Efficiency of prion infection in cells established by transducing the Ifnar1 gene into immortalized Ifnar1 À/À MEFs. Immunoblots show PrP Sc after prion infection with 2 Â 10 À2 % 22 L-brain homogenate. Graphs show quantification of PrP Sc levels in Ifnar1 À/À (white) and Ifnar1transduced (black) cells. **P 5 0.01 versus Ifnar1 À/À . Data are presented as mean AE SEM. Statistical significance was determined using one-way ANOVA, followed by Tukey-Kramer test in multiple comparisons (A) and unpaired Student's t-test (B). 100 dpi and the terminal stage. The concentrations of RO8191 in the brains and spleens of cured mice at 100 dpi were confirmed to be high 8.44 AE 2.1 and 86.46 AE 62.54 mg/g of tissue, respectively, and these concentrations were maintained at the terminal stage (Fig. 7B) . These results suggest that RO8191 might be able to act specifically on the brain and spleen, the organs mainly responsible for establishing prion formation.