FIGURE 4.

IFN‐γ ‐mediated neuroinflammation was concurrent with, but did not precede, Aβ accumulation. (a) IFN‐γ increased by age 18 months in Sgo1^−/+. The amount of IFN‐γ in Sgo1^−/+ brain was low at 12 months of age, but increased by 18 months of age. Protein amounts, measured by immunoblot and normalized with actin amount, are plotted and compared. (b) Microglia infiltration may not accompany IFN‐γ increase at the 12‐18 month transition. Microglia marker Iba1 (measured as in (a)) did not show a significant increase in 18‐month‐old Sgo1^−/+, suggesting that infiltration of microglia may not be significantly increased at this age. (c) IFN‐γ localized in nucleo‐cytoplasm in aged Sgo1^−/+. Distinct localization of IFN‐γ in nucleo‐cytoplasm was observed only in aged (24‐month) samples and was not observed in 18‐month samples. Marked fields are enlarged to show IHC details. IFN‐γ was observed in cell bodies in 24‐month Sgo1^−/+ cortex, while no localized signal was seen in 18‐month Sgo1^−/+ brain samples. Wild‐type controls did not show IFN‐γ at any age. (d) TNF‐α localization in cytoplasm and in nucleo‐cytoplasm. Distinct cell body localization of TNF‐α was observed in Sgo1^−/+ cortex at both 18 and 24 months of age. At 18 months, cytoplasmic staining was evident (enlarged panel), while at 24 months, diffused staining in both nucleoplasm and cytoplasm was common