Fig. 7: Typhoid toxin-induced SASP in senescent macrophages promotes phenotypic characteristics of senescence in T cells.

a Total T cells isolated from wild-type mice were activated with anti-CD3/CD28, labeled with CellTrace Violet, and cultured in supernatants from RAW 264.7 macrophages treated with mock, wild-type (WT) typhoid toxin, or the PltB^S35A mutant. The percentages indicate the proportion of cells that exhibited proliferation 6 days. b–g Murine primary T cells were activated with anti-CD3/CD28 and then restimulated with ionomycin/TPA for 5 h, and the characteristics of cells were determined by co-staining of indicated surface and intracellular proteins. Frequency of live CD4⁺ T cells (CD4⁺) (b). Frequency of cell surface markers KLRG1 (CD4⁺KLRG1⁺) and TIGIT (CD4⁺TIGIT⁺) in CD4 T cells (c, d). Expression of CD28 in CD4⁺ T cells (CD4⁺CD28⁺) (e) determined by mean fluorescence intensities (MFI). Frequency of granzyme B (CD4⁺GzmB⁺) (f) and IFN-γ (CD4⁺IFN-γ⁺) (g) positive cells in CD4 T cells. Data are presented as the mean ± s.d (n = 3). Statistical analysis was performed using unpaired two-sided t-tests; *P  <  0.05, **P  <  0.01, ****P  <  0.0001. h–o, T cells activated as previously described were cultured in supernatants (CM) from RAW 264.7 macrophages treated with mock, WT typhoid toxin, or the PltB^S35A mutant, with or without ddC. T cell proliferation (h), cell cycle (i), cell viability (j), and the expression of indicated surface and intracellular proteins (k–o) in CD4 T cells were analyzed using flow cytometry. Data are presented as the mean ± s.d (n = 3). Statistical analysis was performed using unpaired two-sided t-tests; *P  <  0.05, **P  <  0.01, ****P  <  0.0001. Source data are provided as a Source data file.