Figure 8.

Elevation of exosomal Mir7k in restraint stressed colitis mice activates autophagy via inhibition of STAT3. (A) qPCR analysis showing the levels of miRNAs that were computationally identified to target Stat3 gene expression in plasma exosomes derived from control and restraint stressed mice. (B) qPCR analysis showing the levels of Mir7k in MSCs exposed to control and restraint stressed plasma exosomes. (C) qPCR analysis showing the expression levels of Mir7k in Mir7k mimic- and Mir7k inhibitor-treated MSCs. (D) Western blotting showing the levels of p-STAT3, STAT3, BECN1 and LC3-I/II in Mir7k mimic- and Mir7k inhibitor-treated MSCs. At 3 days after DSS treatment, Mir7k mimic treated-MSCs were infused into control colitis mice and Mir7k inhibitor-treated MSCs were infused into mice subjected to restraint stress. (E) Body weight loss and (F) disease activity index (DAI) were monitored daily during the entire experiment (n = 5 per group) (* P < 0.05, ** P < 0.01, *** P < 0.005, DSS+MSC versus DSS+Mir7k mimic-MSC; # P < 0.05, ## P < 0.01, DSS+Stress+Mir7k KD-MSC versus DSS+Stress+MSC). At 10 days after DSS induction, mice were euthanized; (G) colon length was recorded, and (H) colonic epithelial/crypt destruction and inflammatory cell infiltration were visualized using HE staining (yellow arrows: goblet cells; green arrows: destruction of epithelial layer; red arrows: inflammatory cell infiltration). (I) Colonic damage was analyzed using histological activity index (HAI). (J, K) Splenocytes were harvested and the ratios of CD4⁺ IL17A⁺ Th17 cells and CD4⁺ CD25⁺ FOXP3⁺ Tregs among CD4⁺ T cells in the spleen were determined using flow cytometry. All results were verified in three independent experiments. A two-tailed Student’s t test (A, B) and one-way ANOVA with Bonferroni’s comparison test (C, E, F, G, I, J, K) were used for statistical analysis. Error bars represent the mean ± s.d. ***P < 0.005; **P < 0.01; *P < 0.05; KD, knockdown