Fig. 6: Age-dependent accumulation of T cells in the mouse hippocampus.
a, Representative images showing age-dependent accumulation of T cells in the mouse hippocampus. b, Representative images showing age-dependent accumulation of IFN-γ-responding (STAT1+) cells in the mouse hippocampus. c, Quantitation of T cells (upper) in hippocampus among different ages (young: 20 ± 9 cells; middle-age: 374 ± 63 cells; old: 1,055 ± 271 cells; two-tailed unpaired t-test with Welch’s correction, **P = 0.0023 between young and middle-age, *P = 0.0346 between middle-age and old, **P = 0.0042 between young and old) and STAT1+ cells (lower) in hippocampus among different ages (young: 28 ± 6 cells; middle-age: 373 ± 82 cells; old: 1,297 ± 344 cells; two-tailed unpaired t-test with Welch’s correction, **P = 0.0054 between young and middle-age, *P = 0.0363 between middle-age and old, *P = 0.0102 between young and old). d, Illustration of hippocampal subregions. e, Radar plots showing the spatial distribution of T cells (left) (young: hilus 5.0%, GCL 5.0%, ML 27.5%, SLM 41.3%, SR 11.3%, SP 7.5%, SO 2.4%; middle-age: hilus 5.6%, GCL 3.2%, ML 11.5%, SLM 47.2%, SR 16.3%, SP 8.5%, SO 7.7%; old: hilus 4.5%, GCL 6.9%, ML 11.5%, SLM 43.9%, SR 17.4%, SP 8.9%, SO 6.9%) and STAT1+ cells (right) (young: hilus 0.0%, GCL 7.3%, ML 4.2%, SLM 28.1%, SR 9.4%, SP 20.8%, SO 30.2%; middle-age: hilus 5.4%, GCL 7.8%, ML 14.8%, SLM 37.9%, SR 13.2%, SP 7.8%, SO 13.1%; old: hilus 3.0%, GCL 5.7%, ML 12.2%, SLM 43.9%, SR 16.1%, SP 8.8%, SO 10.3%) within hippocampal subregions. f, Correlation between the number of T cells and STAT1+ cells in the old hippocampus. g, Rendered images showing correlated spatial distribution of T cells (blue dots) and STAT1+ cells (red dots) in the old mouse hippocampus. h, Representative images showing that most T cells in the old mouse DG were CD8+ (n = 10 mice). i, Representative images showing the inflammatory and cytotoxic phenotypres of CD8+ T cells in the old mouse DG (n = 4 mice). j, Schematic illustration of the pro-inflammatory and cytotoxic phenotypes of T cells in the old mouse hippocampus. GCL, granule cell layer; ML, molecular layer; SLM, stratum lacunosum-moleculare; SO, stratum oriens; SP, stratum pyramidale; SR, stratum radiatum. All data are presented as mean ± s.e.m. Scale bars, 100 μm (20 μm zoom-in panels) (a,b,d) and 20 μm (5 μm zoom-in panels) (h–l).
