Fig 2: GMSC-Exo reduces Th1 and Th17 cytokine production and increases Treg cytokine production in vivo, partially via IL-17RA-Act1-TRAF6-NF-?B signal pathway. (A-E) The expression of serum cytokines IFN-?, IL-17A, IL-10, TNF-a and IL-6 in CIA mice was determined by ELISA. Data are mean ± SD, n = 3 mice. (F) Total proteins were extracted from the paw of CIA mice after mouse sacrifice. The experiments were performed in three independent experiments. The main component proteins of IL-17RA-Act1-TRAF6-NF-?B signal pathway expression were analyzed by Western blot. (G) The relative density of IL-17RA, TRAF6, Act1 and NF-?B p65/105 to GAPDH is shown by bar graph. One-way ANOVA was used to compare different groups. Data are mean ± SD, n = 3 independent experiments. *p < 0.05, **p < 0.01. CIA, collagen-induced arthritis; ELISA, enzyme-linked immunosorbent assay; GMSC, gingival mesenchymal stem cells; GMSC-Exo, gingival mesenchymal stem cell-derived exosomes; NS, not significant; PBS, phosphate-buffered saline

Fig 3: GMSC-Exo exhibited immunosuppressive effects in vitro. CFSE-labeled mouse CD4+ T cells were stimulated with soluble anti-CD28 and co-cultured with gradient doses of GMSC-Exo or GMSC for 72 h. Then, the proliferation of CD4+ T cells or Th1, Th17 and Treg subsets was analyzed by flow cytometry (A-G), and the cytokines (IFN-?, IL-17A and IL-10) were detected by ELISA methods from supernatant of co-culture (H-J). (A, B, C) The representative flow cytometry images show the expression of CFSE+CD4+, CFSE+CD4+IL-10+Treg, CFSE+CD4+INF-?+Th1 and CFSE+CD4+IL-17A+ Th17 cells. Data are representative of three separate experiments. (D-G) Histograms show the percentages of CFSE+CD4+, CFSE+CD4+IL-10+Treg, CFSE+CD4+INF-?+ Th1 and CFSE+CD4+IL-17A+ Th17 cells after co-culture with gradient doses of GMSC-Exo or GMSC. Compared to control group (only CD4+ T cells, without co-culture with GMSC or GMSC-Exo): *p < 0.05, **p < 0.01. Comparison between groups treated with different doses of GMSC or GMSC-Exo: # p < 0.05, ## p < 0.01. After GMSC/GMSC-Exo treatment, the proliferation of CD4+INF-?+ Th1 or CD4+IL-17A+ Th17 cells was down-regulated significantly, while that of CD4+IL-10+Treg or CD4+ T cells was up-regulated significantly. The data are presented as the mean ± SEM from three separate experiments. Data are representative of three separate experiments. (H-J) The levels of IL-10, IFN-? and IL-17A were shown. After GMSC or GMSC-Exo treatment, the level of IL-10 was up-regulated in a dose-dependent manner, while that of IFN-? or IL-17A was down-regulated significantly. Compared to control group (only CD4+ T cells, without co-culture with GMSC or GMSC-Exo): *p < 0.05, **p < 0.01. Comparison between groups treated with different doses of GMSC or GMSC-Exo: # p < 0.05, ## p < 0.01. The data are presented as the mean ± SEM from three separate experiments. ELISA, enzyme-linked immunosorbent assay; GMSC, gingival mesenchymal stem cells; GMSC-Exo, gingival mesenchymal stem cell-derived exosomes

Fig 4: GMSC-Exo therapy influences the polarization of Th cells in vivo. (A, C, E) Representative flow cytometry images show the expression of CD4+INF-?+ Th1, CD4+IL-17A+ Th17 cells and CD4+CD25+FoxP3+ Treg in the spleens and LNs of three groups of CIA mice. (B, D, F) GMSC-Exo and GMSC significantly decreased the percentage of CD4+INF-?+ Th1 and CD4+IL-17A+ Th17 cells in the mouse spleen and LN, and increased the percentage of CD4+CD25+FoxP3+ Treg, whereas PBS did not significantly alter the frequencies of the subset Th cells in the CIA mice. n = 6 in each group. The animal experiments were performed in three independent experiments. *p < 0.05, **p < 0.01. Values are given as mean ± SD. CIA, collagen-induced arthritis; GMSC, gingival mesenchymal stem cells; GMSC-Exo, gingival mesenchymal stem cell-derived exosomes; LNs, lymph nodes; NS, not significant; PBS, phosphate-buffered saline

Fig 5: NTB-DCs vaccine significantly increased the antibody and cellular immune responses. (A) Six-week-old C57BL/6J APCMin/+ mice were given AOM for 4 weeks and administered F. nucleatum for 8 weeks. At week 20, the mice were immunized twice a week with DCs control, TBI-DCs, BNE-DCs vaccine and NTB-DCs vaccine for 4 weeks. (B) TBI and NTB adjuvant increased the antibody responses. Mice (n = 10) were immunized DCs control, TBI-DCs, BNE-DCs vaccine and NTB-DCs vaccine. At week 24, mice sera were harvested, IgG and IgG subgroups were detected by ELISAs. (C) TBI and NTB adjuvant significantly increased the cellular immune response. Splenocytes of immunized mice (n=10) were stimulated with antigen for 3 days. The levels of IFN-?, interleukin-4 (IL-4), IL-12p40 and IL-17A in supernatant were determined using the corresponding ELISA kit. (D) ELISPOT analysis on IFN-? and IL-17A spot-forming cells among splenocytes. The results are shown as the means ± SD. *P <0.05; **P < 0.01; ***P < 0.001.