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. 2021 May 5;12:2537. doi: 10.1038/s41467-021-22755-3

Fig. 3. IFN-γ-dependent inflammation induced by Salmonella YB1 infection facilitates the suppression of cancer metastasis.

Fig. 3

a Quantification (two-tailed unpaired t-tests, n = 8 per group) of 4T1 lung metastases in mice treated with PBS, YB1, heat-killed YB1, and E. coli DH10B, respectively, on day 0. 4T1 cancer cells were intravenously inoculated on day 13 and lung metastasis was quantified on day 27. Kinetics of cytokine levels in the serum of these BALB/c mice were monitored (n = 4 per group) (b). Conc, concentration. c Quantification (two-tailed unpaired t-tests) of 4T1 lung metastases after YB1-induced inflammation was inhibited by prednisolone in the 4T1-BALB/c experimental metastasis model (n = 6 Pred/YB1, n = 5 others). Pred, prednisolone. d Quantification (two-tailed unpaired t-tests) of 4T1 lung metastases following antibody-mediated depletion of TNF-α and IFN-γ in the 4T1-BALB/c experimental metastasis model (n = 5 for PBS and YB1/IgG; n = 6 for YB1/anti-TNF-α and YB1/anti-IFN-γ). e Tracking and quantification (two-tailed unpaired t-tests) of 4T1-Luci cells in vivo by luciferase live imaging 3 h after i.v. injection of 4T1-Luci into BALB/c mice pretreated with PBS, YB1 plus isotype IgG, or YB1 plus IFN-γ depletion antibody, respectively. BALB/c mice were pretreated 3 days in advance with PBS or YB1 (n = 5 per group). f Comparison of the anti-metastatic activity of YB1 in wild-type C57BL/6J mice and IFN-γ-knockout (IFN-γ KO) mice based on the experimental metastasis model established with MB49 cancer cells (n = 5 mice per group). Representative lung pictures, H&E-stained whole lung, and magnified H&E-stained lung tissue from each group were shown. Red arrows indicate partial tumor tissues. Plenty of MB49 tumor nodules were found in lungs from IFN-γ-knockout mice treated either with PBS or YB1 and wild-type mice treated with PBS. g Quantification of 4T1 lung metastases (two-tailed unpaired t-tests) after treatment with recombinant IFN-γ compared to YB1 or PBS treatment. This experiment was based on the 4T1-BALB/c experimental metastasis model (n = 5 per group). All data are presented as mean values ± SEM. All displayed are one representative experiment of two independent experiments. Source data are provided as a Source Data file.