Fig. 7

Intestinal γδ T cells secrete miRNAs to promote Ruminococcus gnavus growth and restore oral tolerance. a, b Nanostring miRNA analysis of statistically different up and downregulated fecal miRNAs. γδ^−/−/WT Log2 ratio with p < 0.05 is shown (a) and total reads of let-7f in the feces from WT and γδ^−/− mice (b); n=5 mice/group; Student’s t test. c IEL and LP γδ T cells were sorted and let-7f expression measured by RT-qPCR. Relative expression to miR-21 (the most abundant fecal miRNA) is shown. Data are mean ± SEM; n=4 mice pooled into 2 samples. d Bacterial genes of R. gnavus that are predicted to be targeted by let-7f, indicated by sequence blast and predicted for secondary structure property (minimum free energy, mfe) by RNAhybrid. e Let-7f or its scrambled sequence (Scr) were orally given to WT and γδ^−/− mice for 7 consecutive days at a dose of 1000 pmol/mouse/day. On the last day of miRNA administration, fecal samples from WT and γδ^−/− mice were collected and RT-qPCR performed to detect R. gnavus levels. Data are mean ± SEM; n=6 mice/group; Student’s t test. f Let-7f or its scrambled sequence (Scr) were orally given to WT and γδ^−/− mice for 7 consecutive days at a dose of 1000 pmol/mouse/day. On the last day of miRNA administration, half of each group were fed OVA in the drinking water for 5 days. OVA continuous feeding was stopped and 2 days later mice were immunized with OVA/CFA. g Responsiveness to OVA was measured by splenocyte proliferation upon 100 µg/mL of OVA stimulation 10 days after OVA/CFA immunization. Data are mean ± SEM; n=5–6 mice/group; one-way ANOVA. h, i FACS plots and bar graphs showing frequencies of live CD3⁺CD4⁺Foxp3⁺ (h) and CD3⁺CD4⁺IL-17A⁺ (i) from small intestine lamina propria (SILP) of mice orally treated with let-7f or its scrambled sequence one day after the last gavage and before OVA/CFA immunization. Data are mean ± SEM; n=5 mice/group; one-way ANOVA. NS=non-significant, * p < 0.05, ** p < 0.01, *** p < 0.001. Results are representative of at least two independent experiments