Fig. 1

T cells infiltrate the old neurogenic niches and affect the brain microenvironment. a t-SNE projection of the CD45⁺ cells in the SVZ from three young (3 months old) and three old (28–29 months old) mice. Cell types are color-coded and annotated based on the transcriptomic profiles. b Bar plot showing the fraction of cells associated with each cell type in the young and aged SVZ. *P ≤ 0.05 by one-tailed Wilcoxon rank sum test. c Representative confocal microscopic images of young and old SVZs stained for CD31 and CD8a. Nuclei are labeled with DAPI. Scale bar: 200 μm. d Number of CD8⁺ T cells per coronal section in four young (6–8 weeks old) and four aged (18 months old) male mice. *P = 0.0286, Mann–Whitney test, two sided. Data are shown as mean ± s.e.m. e Violin plots showing expression of various T cell activation- (Cd69, Itk), cytokine release- (Ccl5, Xcl1), and cytotoxicity-related (Gzmb, Gzmk) genes in each of three distinct clusters. f Sankey diagram depicting the interaction between T cells and resident cells in the SVZ based on the Reactome term immunoregulatory interactions between a lymphoid and a non-lymphoid cell (R-HSA-198933). The proportional flow represents the number of gene pairs. Gene pairs are listed in Supplementary Table 2