Fig. 1. Typhoid toxin induces cellular senescence and proinflammatory SASP in cells.

a Western blot analysis of THP-1-derived macrophages exposed to typhoid toxin. THP-1-derived macrophages were treated with either wild-type (WT) typhoid toxin or the PltB^S35A mutant at 37 °C for 1 h and then changed to regular growth medium. The cell lysates were collected at indicated time points and subjected to western blot analysis for protein assessment. b, c THP-1-derived macrophages exposed to typhoid toxin exhibited SA-β-gal activity staining. DAPI staining is shown in blue. Scale bars, 0.275 mm. The quantification results are presented as mean ± s.d (n  =  3) (c). Statistical analysis was performed using unpaired two-sided t-tests; **P  <  0.01, ***P  <  0.001. d Principal component analysis (PCA) of transcriptome data for THP-1-derived macrophages exposed to typhoid toxin. e A volcano plot showing gene expression changes in WT typhoid toxin-treated macrophages compared to PltB mutant toxin-treated macrophages, highlighting upregulated genes in red and down-regulated genes in blue (P < 0.05 and fold change >1.5). f Gene set enrichment analysis (GSEA) showing upregulated genes related to cellular senescence in typhoid toxin-treated macrophages compared with the PltB^S35A mutant. A heatmap represents the gene expression levels involved in cellular senescence as determined by RNA-seq. g Additional GSEA was conducted to show Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment in WT typhoid toxin-treated macrophages versus the PltB^S35A mutant, with normalized enrichment scores (NES). h GSEA showing upregulated genes related to the senescence-associated secretory phenotype (SASP) in WT typhoid toxin-treated macrophages compared to the PltB^S35A mutant. A heatmap represents gene expression levels involved in the SASP as determined by RNA-seq. i Cytokine profile of conditional medium obtained from THP-1-derived macrophages exposed to WT typhoid toxin or the PltB^S35A mutant. The SASP factors are enclosed with labels.  j RT-qPCR analysis of mRNA levels of indicated genes in murine bone marrow-derived macrophages (BMDMs) exposed to WT typhoid toxin and the PltB^S35A mutant. Data are presented as mean ± s.d (n  =  3). Statistical analysis was performed using unpaired two-sided t-tests; *P  <  0.05, **P  <  0.01, ***P  <  0.001, ****P  <  0.0001. The western blots shown in (a) are representative of 3 independent experiments. Source data are provided as a Source data file.