Fig. 4: The P. anaerobius-secreted protein lytC_22 induces MDSCs activation.
a–c, MDSCs were treated with broth, PA-CM, heat-treated PA-CM or PK-treated PA-CM. a, Levels of Arg1 and iNOS mRNA, detected by quantitative PCR, in MDSCs. n = 6 (broth, PA-CM); n = 4 (heat-inactivated PA-CM, PK-inactivated PA-CM). b, MFI of Arg1 and iNOS of MDSCs, determined by flow cytometry. c, The function of CD4+ and CD8+ T cells (IFN-γ and GzmB expression) was measured using flow cytometry after co-culture with MDSCs; n = 6 biologically independent samples. d, The Arg1 and iNOS levels of MDSCs treated with recombinant lytC_22 (10 and 20 nM) were determined using quantitative PCR (left) and flow cytometry (right). b,d, n = 3 biologically independent samples. e, CFSE-labelled T cells were co-cultured at different ratios with MDSCs, pretreated with or without (control, Ctrl) lytC_22 (10 nM) for 72 h, and CD4+ and CD8+ T cell proliferation was determined by flow cytometry; n = 5 (solvent blank); n = 4 (lytC_22). Percentages in the flow plots are the percentages of subsequent cell divisions in total CD8+ and CD4+ T cells. f, T cells were co-cultured at a 1:1 ratio with MDSCs, pretreated with or without lytC_22 (10 nM) for 72 h and the MFI of IFN-γ and GzmB in the CD4+ and CD8+ T cell subpopulations was determined; n = 6 (solvent blank) and 4 (lytC_22). a–f, Data are the mean ± s.e.m. P values were calculated using a one-way ANOVA, followed by Tukey’s post-hoc test (a–d); two-way ANOVA, followed by Bonferroni’s post-hoc test (e) or an unpaired two-tailed Student’s t-test (f).
