Fig. 8: Loss of immune privilege leads to reduced neurogenic activity in the BBB-deficient mouse brain.

a, Schematic illustration of the pericyte-deficient and inflammatory phenotypes of the Pdgfb^ret/ret mouse model. b, Immunofluorescent staining of pericyte marker (CD13) showing deficient pericyte network and infiltrated CD8⁺ T cells in the Pdgfb^ret/ret mouse hippocampus compared to the control (Pdgfb^ret/+) animals. c, Representative images showing reduced proliferating cells (Ki67⁺) (left) and reduced newly born neuronal cells (DCX⁺) (right) in the Pdgfb^ret/ret mouse SGZ. d, Quantitation of Ki67⁺ cells in the SGZ between Pdgfb^ret/+ and Pdgfb^ret/ret (Pdgfb^ret/+: 1,396 ± 42 cells, n = 6 mice; Pdgfb^ret/ret: 937 ± 64 cells, n = 6 mice; two-tailed unpaired t-test with Welch’s correction, ***P = 0.0002). e, Quantitation of DCX⁺ cells in the SGZ between Pdgfb^ret/+ and Pdgfb^ret/ret (Pdgfb^ret/+: 4,457 ± 155 cells, n = 6 mice; Pdgfb^ret/ret: 3,673 ± 137 cells, n = 6 mice; two-tailed unpaired t-test with Welch’s correction, **P = 0.0037). f, Representative images showing the existence of SOX2⁺NEUROD1⁺ neuroblasts in both Pdgfb^ret/+ and Pdgfb^ret/ret mouse SGZ. g, Quantitation of the percentage of SOX2⁺NEUROD1⁺ neuroblasts among all neuroblasts in the SGZ between Pdgfb^ret/+ and Pdgfb^ret/ret (Pdgfb^ret/+: 9.0 ± 0.6%, n = 6 mice; Pdgfb^ret/ret: 8.1 ± 0.3%, n = 6 mice; two-tailed unpaired t-test with Welch’s correction, NS P = 0.2057). h, Schematic illustration of the interaction between environmental factors and neurogenic activity. Whereas proliferation and generation of DCX⁺ cells are impaired in Pdgfb^ret/ret mice (dashed line), delayed maturation of neuroblasts is not affected in Pdgfb^ret/ret mice. All data are presented as mean ± s.e.m. Scale bars, 100 μm (a,c) and 20 μm (e). MO, months old; NS, not significant.

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