Fig. 6: Intestinal late enterocytes process and present Salmonella antigens to CD8⁺ T cells for their early activation.

A New RNA imaging of small intestines. Mice were infected with Salmonella and new RNA was labeled with EU (red). Scale bar, 100 μm. B UMAP plot of intestinal epithelial cells and NTR of each Salmonella infection time points. ISC, intestinal stem cell; TA, transit amplifying cell; EEC, enteroendocrine; E enterocyte. C Bubble plot showing log-normalized new RNA expression in IECs. D Intercellular communication network between IECs and immune cells at 2 h post Salmonella infection. Line width was proportional to the number of interactions. E Comparison of signaling pathways between 2 h and 0 h state based on the relative information flow. F Scatter plots showing outgoing and incoming interaction strength of MHC-I pathway at 2 h post infection. G Expression of Il15 in IECs. Late E was marked. H Flow cytometry showing MHC-I expression in CD45⁺ immune cells and Slc15a1⁺ late E at 0 h and 6 h post Salmonella infection. Mean fluorescence intensities (MFI) were calculated. n = 5 biologically independent replicates. Results are shown as mean ± SEM. p values were determined by two-way ANOVA. I Immunofluorescence imaging of MHC-I expression in enterocytes and CD8⁺ T cells at 6 h post Salmonella infection. Scale bar, 50 μm. J Late E or DCs from uninfected or Salmonella infected mice (6 h) were sorted and incubated with DQ-Ova. DQ-OVA antigen processing ability was detected via flow cytometry. n = 5 biologically independent replicates. Results are shown as mean ± SEM. p values were determined by one-way ANOVA. K Flow cytometry analysis showing presentation of SIINFEKL-H2Kb complex in late E and DCs at each time points post S.T-Ova infection. MFI was calculated. n = 6 biologically independent replicates. Results are shown as mean ± SEM. p values were determined by two-way ANOVA. L Late E induced CD8⁺ T cell proliferation in vitro. Flow cytometry analysis showing CFSE signals of naive CD8⁺ T cells from OT-I mice that were cultured alone or co-cultured with late E or DCs from uninfected and S.T-Ova infected mice. n = 5 biologically independent replicates. Results are shown as mean ± SEM. p values were determined by one-way ANOVA. Results are representative of at least three independent experiments. Source data are provided as a Source Data file.