Fig 2: MCC950 treatment enhances myeloid-derived suppressor cell (MDSC) function in acute liver injury. (A) Representative images of MDSC in spleen, blood, and liver detected by flow cytometry in CCl4-treated mice pretreated with vehicle or MCC950 on days 1, 2, and 3. MDSC was marked as CD11b+Gr-1+. (B) Time points of MDSC percentages in spleen. (C) Time points of MDSC percentages in peripheral blood. (D) Time points of MDSC percentages in liver. Data are presented as mean ± SEM. NS: No significance. *p < 0.05, **p < 0.01. Intergroup differences are determined by the Student's t-test.

Fig 3: CAF-1 maintains the myeloid stem and progenitor cell state.a Derivation of Chaf1b-inducible iGMPs from Lys-GFP bone marrow cells by transducing the HOXA9 TF fused to the ligand-binding domain of the G400V mutant estrogen receptor22,24 and IPTG-inducible shRNA lentiviral vectors (LacO-shRNA), expressing either an shRNA targeting Chaf1b (shChaf1b) or a spacer control sequence (shCTRL). Withdrawal of estradiol (-E2) allows for deactivation of HOXA9 (HOXA9 OFF) and IPTG treatment of shChaf1b expressing iGMPs results in CAF-1 depletion (CAF-1 OFF). Cells are analyzed for differentiation 4 days post treatment. b Western blot analysis of two independent subclones expressing either shChaf1b or shCTRL treated with IPTG. Two independent experiments were performed with all four subclones with similar results, but one representative experiment is shown. c Proportion of Lysozyme-GFP-positive cells (%GFP+) for shChaf1b and shCTRL clones under +IPTG or -E2 treatments. d Flow cytometric analysis of GFP signal for shChaf1b clone #1 shown in c under uninduced (UN), CAF-1 OFF (+IPTG) or HOXA9 OFF (-E2) conditions. e Flow cytometric analysis of three neutrophil markers (GFP, CD11b, and Gr1) in CAF-1 OFF cells overexpressing retroviral vectors with empty control (MSCV-EV) or shRNA-resistant CHAF1B (MSCV-CHAF1B). Mean and standard deviation of mean fluorescence intensity (MFI) is shown for n = 3 independent experiments. Two-way ANOVA with Sidak’s correction. f Flow cytometric analysis of GFP signal for the rescue experiment as in e for two independent subclones. g, h RT-qPCR and western blot analysis in HOXA9 and HOXB8 iGMP cell lines transduced with lentiviral vectors constitutively expressing shRNAs targeting Chaf1b (shChaf1b-1 or shChaf1b-2) or a luciferase shRNA control (shCTRL). g The mean and standard deviation of Chaf1b mRNA fold change expression of n = 3 independent experiments. h Representative western blot of three independent experiments with similar results. i–j Flow cytometric analysis of HOXA9 and HOXB8 iGMPs transduced with shChaf1b-1, shChaf1b-2, or shCTRL. Representative GFP signal is shown in i with the mean and standard deviation of % GFP+ population for n = 3 independent experiments shown in j. Two-way ANOVA with Dunnett’s test. *p < 0.0001. Source data are provided as a Source Data file.

Fig 4: ZQT induced apoptosis in G-MDSCs in TME and inhibited its immunosuppressive activity by activating the STAT3/S100A9/Bcl-2/caspase-3 signaling pathway. Mice were treated with anti-Ly6G neutralizing antibody or isotype control by intraperitoneal injection for 14 days before surgery, after which model mice were given maintenance treatment every other day. (a, b) The bioluminescence images of model mice on day 7 and day 28 after surgery. (c) Survival curves. (d, e) The percentage of G-MDSCs, CD3+ T cells, CD4+ T cells, and CD8+ T cells in tumor tissue were analyzed by flow cytometry. (f, g) CD3+ T cells isolated from the tumor tissue of tumor-bearing C57BL/6 mice in different groups were cocultured with LLC cells for 4 h before they were incubated with CD3, CD8, and CD107a antibodies. Events shown were finally gated on CD3 and CD8. (h) ELISA analysis for the expression of IFN-? in cells from tumor tissue. (i) RT-qPCR analysis of Arg-1, iNOS, and S100A9 gene expression and flow cytometry for ROS production. (j) IHC staining for Ly6G and CD8 in tumor tissue (scale bar: 50 µM). n = 5. Data are expressed as the mean ± SD. n/s: nonstatistical significance. *p < 0.05; **p < 0.01; ***p < 0.001.

Fig 5: Cytokines and chemokines secreted by CD11b+Gr1+ cells increase fibroblast migration.(A) Antibody array analysis of proteins secreted by CD11b+Gr1+ cells compared to fibroblasts. Although 144 proteins were assayed, only proteins predominantly expressed in CD11b+Gr1+ cells are shown. (B) Purified cytokine treatment of fibroblasts increases migration through Transwell chambers. (C) Combinations of several cytokines and chemokines increase fibroblast migration beyond treatment with a single cytokine/chemokine. Concentrations are same as on (B), * – p<0.05, ** – p<0.01, *** – p<0.001 compared to untreated; #: p<0.01 compared to all other treatments. (D) Inhibition of FGFR1 Kinase by PD173074 (5 nM) prevents fibroblast migration towards conditioned medium from CD11b+Gr1+ cells. ** – p<0.01, *** – p<0.001 relative to control medium.